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Filed Pursuant to Rule 424(b)(5)
Registration No. 333-202692

This preliminary prospectus supplement relates to an effective registration statement under the Securities Act of 1933, as amended, but is not complete and may be changed. This preliminary prospectus supplement and the accompanying prospectus are not offers to sell these securities and are not soliciting an offer to buy these securities in any jurisdiction where the offer or sale is not permitted.

Subject to Completion

Preliminary Prospectus Supplement dated September 27, 2016

PRELIMINARY PROSPECTUS SUPPLEMENT

(To Prospectus dated September 27, 2016)

15,000,000 Depositary Shares

Each Representing a 1/20th Interest in a Share of

    % Series B Mandatory Convertible Preferred Stock

Great Plains Energy Incorporated

We are offering 15,000,000 depositary shares (the “Depositary Shares”), each of which represents a 1/20th interest in a share of our     % Series B Mandatory Convertible Preferred Stock, without par value (the “Mandatory Convertible Preferred Stock”). The shares of Mandatory Convertible Preferred Stock will be deposited with Computershare Trust Company, N.A., as bank depositary, pursuant to a deposit agreement. Holders of the Depositary Shares will be entitled to a proportional fractional interest in the rights and preferences of the Mandatory Convertible Preferred Stock, including conversion, dividend, liquidation and voting rights, subject to the provisions of such deposit agreement. We will receive all of the net proceeds from this offering.

Dividends on the Mandatory Convertible Preferred Stock will be payable on a cumulative basis when, as and if declared by our board of directors or an authorized committee thereof, at an annual rate of     % of the liquidation preference of $1,000 per share. We may pay declared dividends in cash or, subject to certain limitations, in shares of our common stock, without par value (our “common stock”), or by delivery of any combination of cash and shares of our common stock, at our election, subject to certain limitations, on March 15, June 15, September 15 and December 15 of each year, commencing on December 15, 2016, and to, and including, September 15, 2019.

Each share of our Mandatory Convertible Preferred Stock has a liquidation preference of $1,000 (and, correspondingly, each Depositary Share represents a liquidation preference of $50). Unless earlier converted or redeemed, each share of Mandatory Convertible Preferred Stock will automatically convert on the third business day immediately following the last trading day of the final averaging period defined below (the “mandatory conversion date”) into between              and              shares of our common stock, subject to anti-dilution adjustments, depending on the average VWAP (as defined herein) per share of our common stock over the 20 consecutive trading day period commencing on, and including, the 22nd scheduled trading day prior to September 15, 2019 (the “final averaging period”). At any time prior to the mandatory conversion date, a holder of 20 Depositary Shares may cause the bank depositary to convert one share of our Mandatory Convertible Preferred Stock, on such holder’s behalf, into shares of our common stock at the minimum conversion rate of              shares of our common stock per share of Mandatory Convertible Preferred Stock, subject to anti-dilution adjustments. If a holder of 20 Depositary Shares causes the bank depositary to convert one share of Mandatory Convertible Preferred Stock, on such holder’s behalf, during a specified period beginning on the effective date of a fundamental change (as defined herein), such share of Mandatory Convertible Preferred Stock will be converted into shares of our common stock at the fundamental change conversion rate (as defined herein), and such holder will also be entitled to receive a fundamental change dividend make-whole amount and accumulated dividend amount (each as defined herein).

Concurrently with this offering of the Depositary Shares, we are offering by means of a separate prospectus supplement 52,600,000 shares of our common stock (or 60,490,000 shares of our common stock if the underwriters of that offering exercise in full their option to purchase additional shares of our common stock) (the “concurrent offering”). This offering of the Depositary Shares and the concurrent offering are not contingent on one another.

We intend to use the net proceeds of this offering, together with the net proceeds of the concurrent offering, to finance a portion of the cash consideration payable in connection with the Merger (as defined herein). The closings of this offering and the concurrent offering are not conditioned on the closing of the Merger, which, if completed, will occur subsequent to the closing of this offering. See “Prospectus Supplement Summary — Recent Developments — Pending Westar Merger” and “Use of Proceeds.” If the Merger has not closed on or prior to November 30, 2017 or if an acquisition termination event (as defined herein) occurs, we may, at our sole option, redeem the Mandatory Convertible Preferred Stock, in which case the bank depositary will redeem the Depositary Shares, in each case, as further described herein.

Prior to this offering, there has been no public market for the Depositary Shares. We intend to apply to list the Depositary Shares on the New York Stock Exchange (the “NYSE”) under the symbol “GXPPRB.” Our common stock is listed on the NYSE under the symbol “GXP.” On September 26, 2016, the last reported sale price of our common stock on the NYSE was $27.94 per share.

Investing in the Depositary Shares involves risks. See “Risk Factors ” beginning on page S-26 in this prospectus supplement and beginning on page 5 of the accompanying prospectus.

Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

We have granted the underwriters an option, exercisable within a 30-day period beginning on, and including, the date of this prospectus supplement, to purchase up to 2,250,000 additional Depositary Shares at the public offering price, less the underwriting discount. See “Underwriting.”

The underwriters expect to deliver the Depositary Shares against payment therefor on or about October     , 2016.

Goldman, Sachs & Co.

Prospectus Supplement dated September     , 2016

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ABOUT THIS PROSPECTUS SUPPLEMENT

This document is in two parts. The first part is this prospectus supplement, which describes the terms of this offering. The second part is the accompanying prospectus dated September 27, 2016, which we refer to as the “accompanying prospectus.” The accompanying prospectus contains a description of the securities we may offer under the registration statement of which this prospectus supplement and the accompanying prospectus form a part and gives more general information, some of which may not apply to this offering of Depositary Shares.

This prospectus supplement, the accompanying prospectus and any free-writing prospectus that we file with the Securities and Exchange Commission (the “SEC”) contain and incorporate by reference information that you should consider when making your investment decision. We have not, and the underwriters have not, authorized anyone to provide you with different information. If anyone provides you with different or inconsistent information, you should not rely on it. We are not, and the underwriters are not, making an offer to sell these securities in any jurisdiction where the offer or sale is not permitted. You should assume that the information appearing in this prospectus supplement, the accompanying prospectus and the documents incorporated by reference is accurate only as of their respective dates. Our business, financial condition, results of operations and prospects may have changed materially since those dates.

Before you invest in the Depositary Shares, you should carefully read the registration statement (including the exhibits thereto) of which this prospectus supplement and the accompanying prospectus form a part, this prospectus supplement, the accompanying prospectus and the documents incorporated by reference into this prospectus supplement and accompanying prospectus. The incorporated documents are described in this prospectus supplement under “Where You Can Find More Information.”

Unless the context otherwise requires or as otherwise indicated, when we refer to “Great Plains Energy,” the “Company,” “we,” “us” or “our” in this prospectus supplement or the accompanying prospectus or when we otherwise refer to ourselves herein or therein, we mean Great Plains Energy Incorporated and its subsidiaries, unless the context clearly indicates otherwise.

CAUTIONARY STATEMENTS REGARDING CERTAIN FORWARD-LOOKING INFORMATION

This prospectus supplement, the accompanying prospectus and the documents incorporated or deemed incorporated by reference as described under the heading “Where You Can Find More Information” contain forward-looking statements that are not based on historical facts. In some cases, you can identify forward-looking statements by use of the words “may,” “should,” “expect,” “plan,” “anticipate,” “estimate,” “predict,” “potential” or “continue.” Forward-looking statements include, but are not limited to, statements relating to Great Plains Energy’s proposed acquisition of Westar Energy, Inc., a Kansas corporation (“Westar”), the outcome of regulatory proceedings, cost estimates of capital projects and other matters affecting future operations. These forward-looking statements are based on assumptions, expectations and assessments made by our management in light of their experience and their perception of historical trends, current conditions, expected future developments and other factors they believe to be appropriate. Any forward-looking statements are not guarantees of our future performance and are subject to risks and uncertainties, including those discussed under the heading “Risk Factors” in this prospectus supplement and in our other filings with the SEC. These risks and uncertainties could cause actual results, developments and business decisions to differ materially from those contemplated or implied by forward-looking statements. Consequently, you should recognize these statements for what they are and we caution you not to rely upon them as facts. We claim the protection of the safe harbor for forward-looking statements contained in the Private Securities Litigation Reform Act of 1995 for all forward-looking statements. We disclaim any duty to update the forward-looking statements, which apply only as of the date of this prospectus supplement. Some of the factors that may cause actual results, developments and business decisions to differ materially from those contemplated by these forward-looking statements include the following:

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This list of factors is not all-inclusive because it is not possible to predict all factors.

In addition, actual results may differ materially from those contemplated in any forward-looking statement due to the timing and likelihood of the closing of our pending acquisition of Westar and the other risk factors discussed under Item 1A of Part II of our Quarterly Report on Form 10-Q for the quarter ended June 30, 2016, which is incorporated by reference.

WHERE YOU CAN FIND MORE INFORMATION

We file annual, quarterly and current reports, and proxy statements and other information, with the SEC through the SEC’s Electronic Data Gathering, Analysis and Retrieval system and these filings are publicly available through the SEC’s website (http://www.sec.gov). You may read and copy such material at the SEC’s Public Reference Room at 100 F Street, N.E., Washington, D.C. 20549. You may obtain information on the operation of the Public Reference Room by calling the SEC at 1-800-SEC-0330.

The SEC allows us to “incorporate by reference” into this prospectus supplement the information we file with it. This means that we can disclose important information to you by referring you to the documents containing the information. The information we incorporate by reference is considered to be included in and an important part of this prospectus supplement and should be read with the same care. Information that we file later with the SEC that is incorporated by reference into this prospectus supplement will automatically update and supersede this information. Our Annual Report on Form 10-K and our Quarterly Reports on Form 10-Q listed below have been filed with the SEC on a combined basis by us and one of our subsidiaries, KCP&L (as defined herein). We are only incorporating the information that relates to us and, where required, the information that relates to KCP&L. We are incorporating by reference into this prospectus supplement the following documents that we have filed with the SEC and any subsequent filings we make with the SEC under Section 13(a), 13(c), 14 or 15(d) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”) (excluding information deemed to be furnished and not filed with the SEC), until the offering of the securities described in this prospectus supplement is completed:

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Our website is www.greatplainsenergy.com. Information contained on our website is not incorporated herein except to the extent specifically so indicated. We make available, free of charge, on or through our website, our annual reports on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K, and amendments to those reports filed or furnished pursuant to Section 13(a) or 15(d) of the Exchange Act as soon as reasonably practicable after we electronically file such material with, or furnish it to, the SEC. In addition, we make available on or through our website all other reports, notifications and certifications filed electronically with the SEC. You may obtain a free copy of our filings with the SEC by writing or telephoning us at the following address: Great Plains Energy Incorporated, 1200 Main Street, Kansas City, Missouri 64105 (Telephone No.: 816-556-2200), Attention: Corporate Secretary, or by contacting us on our website.

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RISK FACTORS

An investment in our common stock is subject to various risks. These risks should be considered carefully with the information provided elsewhere and incorporated by reference in this prospectus supplement and the accompanying prospectus before deciding to invest in the Depositary Shares. In addition to the risk factors set forth below, please read the information included or incorporated by reference under “Risk Factors” and “Cautionary Statements Regarding Certain Forward-Looking Information” in this prospectus supplement, our Annual Report on Form 10-K for the year ended December 31, 2015 and our Quarterly Reports on Form 10-Q for the quarters ended March 31, 2016 and June 30, 2016 for a description of additional uncertainties associated with our business, results of operations and financial condition and the forward-looking statements included or incorporated by reference in this prospectus supplement and the accompanying prospectus, including risk factors relating to the Merger discussed under Item 1A of Part II of our Quarterly Report on Form 10-Q for the quarter ended June 30, 2016, which is incorporated by reference. As used in this section, “we,” “our,” “us” and the “Company” refer to Great Plains Energy Incorporated and not to any of its subsidiaries.

Risks Related to the Depositary Shares, the Mandatory Convertible Preferred Stock, Our Common Stock and This Offering

You are making an investment decision in the Depositary Shares as well as in the Mandatory Convertible Preferred Stock.

As described in this prospectus supplement, you are investing in Depositary Shares that represent fractional interests in the Mandatory Convertible Preferred Stock. The bank depositary will rely solely on the dividend payments and other distributions on the Mandatory Convertible Preferred Stock it receives from us to fund all dividend payments and other distributions on the Depositary Shares.

You will bear the risk of a decline in the market price of our common stock between the pricing date for the Depositary Shares and the mandatory conversion date.

The number of shares of our common stock that you will receive upon mandatory conversion of the Mandatory Convertible Preferred Stock (and the corresponding mandatory conversion of the Depositary Shares) is not fixed but instead will depend on the applicable market value of our common stock, which is the average VWAP per share of our common stock over the 20 consecutive trading day period commencing on, and including, the 22nd scheduled trading day prior to September 15, 2019. The aggregate market value of our common stock that you would receive upon mandatory conversion of the Mandatory Convertible Preferred Stock may be less than the aggregate liquidation preference of the Mandatory Convertible Preferred Stock represented by your Depositary Shares. Specifically, if the applicable market value of our common stock is less than the initial price of approximately $        , the market value of our common stock that you would receive upon mandatory conversion of each share of the Mandatory Convertible Preferred Stock will be less than the $1,000 liquidation preference per share of Mandatory Convertible Preferred Stock (and, accordingly, the market value of our common stock that you would receive upon mandatory conversion of each Depositary Share would be less than the $50 liquidation preference per Depositary Share), and an investment in the Depositary Shares would result in a loss, assuming that the market value on the mandatory conversion date is the same as the applicable market value of our common stock. Therefore, you will bear the risk of a decline in the market price of our common stock, which decline could be substantial.

The opportunity for equity appreciation provided by your investment in the Depositary Shares is less than that provided by a direct investment in our common stock.

The market value of each share of our common stock that you would receive upon mandatory conversion of each share of the Mandatory Convertible Preferred Stock (and the corresponding mandatory conversion of the Depositary Shares) on the mandatory conversion date will only exceed the liquidation preference of $1,000 per share of the Mandatory Convertible Preferred Stock (and the corresponding liquidation preference of $50 per Depositary Share) if the applicable market value of our common stock exceeds the threshold appreciation price of approximately $        . The threshold appreciation price represents an appreciation of approximately     % over

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the initial price. In this event, on the mandatory conversion date, you would receive approximately     % (which percentage is equal to the initial price divided by the threshold appreciation price) of the value of our common stock that you would have received if you had made a direct investment in our common stock on the date of this prospectus supplement, assuming that the market value on the mandatory conversion date is the same as the applicable market value of our common stock. This means that the opportunity for equity appreciation provided by an investment in the Depositary Shares (and the underlying Mandatory Convertible Preferred Stock) is less than that provided by a direct investment in our common stock.

In addition, if the market value of our common stock appreciates and the applicable market value of our common stock is equal to or greater than the initial price but less than or equal to the threshold appreciation price, the aggregate market value of our common stock that you would receive upon mandatory conversion of the Mandatory Convertible Preferred Stock will only be equal to the aggregate liquidation preference of the Mandatory Convertible Preferred Stock (and, correspondingly, the aggregate market value of our common stock that you would receive upon the corresponding mandatory conversion of the Depositary Shares will only be equal to the aggregate liquidation preference of the Depositary Shares), assuming that the market value on the mandatory conversion date is the same as the applicable market value of our common stock, and you will not realize any equity appreciation on our common stock.

The adjustment to the conversion rate and the payment of the fundamental change dividend make-whole amount upon the occurrence of certain fundamental changes may not adequately compensate you.

If a fundamental change (as defined in “Description of Mandatory Convertible Preferred Stock —Conversion Rights — Early Conversion at the Option of the Holder upon a Fundamental Change”) occurs on or prior to the mandatory conversion date, a holder of 20 Depositary Shares will be entitled to cause the bank depositary to convert one share of our Mandatory Convertible Preferred Stock, on such holder’s behalf, during the fundamental change conversion period at the fundamental change conversion rate (in each case, as defined in “Description of Mandatory Convertible Preferred Stock — Conversion Rights — Early Conversion at the Option of the Holder upon a Fundamental Change”). The fundamental change conversion rate represents an adjustment to the conversion rate otherwise applicable unless the share price is less than $        or above $             (in each case, subject to adjustment). In addition, with respect to Mandatory Convertible Preferred Stock converted during the fundamental change conversion period, you will also receive, among other consideration, a fundamental change dividend make-whole amount. Although this adjustment to the conversion rate and the payment of the fundamental change dividend make-whole amount are designed to compensate you for the lost option value of the Depositary Shares and lost dividends as a result of a fundamental change, they are only an approximation of such lost value and lost dividends and may not adequately compensate you for your actual loss. Furthermore, our obligation to adjust the conversion rate in connection with a fundamental change and pay the fundamental change dividend make-whole amount (whether in cash or shares of our common stock or any combination thereof) could be considered a penalty under state law, in which case your ability to enforce such adjustments would be subject to general principles of reasonableness of economic remedies.

The conversion rate of the Mandatory Convertible Preferred Stock and, in turn, the Depositary Shares may not be adjusted for all dilutive events that may adversely affect the market price of the Depositary Shares or our common stock issuable upon conversion of the Mandatory Convertible Preferred Stock and the Depositary Shares.

The number of shares of our common stock that you are entitled to receive upon conversion of your Depositary Shares representing shares of Mandatory Convertible Preferred Stock is subject to adjustment for stock splits and combinations, dividends and certain other transactions. See “Description of Mandatory Convertible Preferred Stock — Conversion Rights — Conversion Rate Adjustments” for further discussion of anti-dilution adjustments. However, other events, such as third-party tender offers, employee and director equity grants or offerings of our common stock or securities convertible into shares of our common stock for cash or in connection with acquisitions, which may adversely affect the market price of our common stock, may not result in any adjustment. Further, if any of these other events adversely affects the market price of our common stock, it may also adversely affect the market price of the Depositary Shares. In addition, the terms of the Mandatory

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Convertible Preferred Stock and the Depositary Shares do not restrict our ability to offer common stock or securities convertible into common stock in the future or to engage in other transactions that could dilute our common stock. We have no obligation to consider the interests of the holders of the Mandatory Convertible Preferred Stock or the Depositary Shares in engaging in any such offering or transaction.

You will not have any right to require us to redeem the Mandatory Convertible Preferred Stock and, in turn, cause the redemption of the Depositary Shares in the event that an acquisition termination event occurs or the Merger is not completed by November 30, 2017.

You will not have any rights to require us to redeem the Mandatory Convertible Preferred Stock and, in turn, cause the redemption of the Depositary Shares if an acquisition termination event occurs or the Merger is not completed by 5:00 p.m. (New York City time) on November 30, 2017. Further, you will not have any right to require us to redeem the Mandatory Convertible Preferred Stock and, in turn, cause the redemption of the Depositary Shares if, subsequent to the completion of this offering, we or Westar experience any changes in our business or financial condition or if the terms of the Merger or the financing thereof change. Even if we redeem the Mandatory Convertible Preferred Stock (and, accordingly, the bank depositary redeems the Depositary Shares), you may not obtain your expected return and may not be able to reinvest the proceeds from such redemption in an investment that results in a comparable return.

The Mandatory Convertible Preferred Stock is, and, accordingly, the Depositary Shares are, subject to redemption at our option upon the occurrence of an acquisition termination event or if the Merger is not completed on or prior to 5:00 p.m. (New York City time) on November 30, 2017.

Within ten business days following the earlier of (a) the date on which the Merger is terminated or the date on which we determine in our reasonable judgment that the Merger will not occur and (b) 5:00 p.m. (New York City time) on November 30, 2017, if the Merger has not closed on or prior to such time on such date, we may, at our option, in our sole discretion, give notice of an acquisition termination redemption to all holders of the Mandatory Convertible Preferred Stock. If we provide such notice, then, on the acquisition termination redemption date (as defined herein), we will be required to redeem the Mandatory Convertible Preferred Stock, in whole but not in part, at a redemption price equal to $1,000 per share of Mandatory Convertible Preferred Stock (equivalent to $50 per Depositary Share) plus accumulated and unpaid dividends to the date of redemption or, in certain circumstances, at an early redemption price that includes a make-whole adjustment. If we redeem shares of the Mandatory Convertible Preferred Stock held by the bank depositary, the bank depositary will redeem, on the acquisition termination redemption date, the Depositary Shares, as described under “Description of Depositary Shares — Redemption.” Although the Depositary Shares redemption price is designed to compensate you for the lost option value of your Depositary Shares and lost dividends as a result of the acquisition termination redemption, it is only an approximation of such lost value and may not adequately compensate you for your actual loss.

The proceeds of this offering will not be deposited into an escrow account in favor of holders of Mandatory Convertible Preferred Stock or Depositary Shares pending any acquisition termination redemption of the Mandatory Convertible Preferred Stock and the Depositary Shares. Our ability to pay the acquisition termination make-whole amount to holders of the Mandatory Convertible Preferred Stock in connection with an acquisition termination redemption (and, accordingly, the bank depositary’s ability to pay the Depositary Shares redemption price to holders of the Depositary Shares) may be limited by our then-existing financial resources, and sufficient funds may not be available when necessary to make any required purchases of the Mandatory Convertible Preferred Stock (and, accordingly, Depositary Shares) following our election to redeem the Mandatory Convertible Preferred Stock.

Recent regulatory actions may adversely affect the trading price and liquidity of the Depositary Shares.

Investors in, and potential purchasers of, the Depositary Shares who employ, or seek to employ, a convertible arbitrage strategy with respect to the Depositary Shares may be adversely impacted by regulatory developments that may limit or restrict such a strategy. The SEC and other regulatory and self-regulatory authorities have implemented various rules and may adopt additional rules in the future that restrict and

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otherwise regulate short selling and over-the-counter swaps and security-based swaps, which restrictions and regulations may adversely affect the ability of investors in, or potential purchasers of, the Depositary Shares to conduct a convertible arbitrage strategy with respect to the Depositary Shares. This could, in turn, adversely affect the trading price and liquidity of the Depositary Shares.

The concurrent offering of our common stock, and the possibility of the sale of our common stock in the future, could lower the market price for our common stock and adversely impact the trading price of the Depositary Shares.

Concurrently with this offering, we are offering up to 52,600,000 shares of our common stock, plus up to 7,890,000 additional shares of our common stock if the underwriters in that offering exercise in full their option to purchase additional shares of our common stock. This offering is not conditioned on the closing of the concurrent offering, and the concurrent offering is not conditioned on the closing of this offering. In addition, in the future, we may issue additional securities to raise capital. We may also acquire interests in other companies by using a combination of cash and common stock or just common stock. We may also issue securities convertible into our common stock. Additionally, in connection with the Merger, up to approximately 45 million shares of our common stock will be issued to the Westar shareholders. Any of these events may dilute your ownership interest in the Company and have an adverse impact on the price of our common stock and, in turn, the Depositary Shares. In addition, a substantial number of shares of our common stock is reserved for issuance upon the exercise of stock options and upon conversion of the Mandatory Convertible Preferred Stock and the Series A Preferred (if issued). We cannot predict the size of future issuances or the effect, if any, that they may have on the market price for our common stock. The issuance and sale of substantial amounts of our common stock, or the perception that such issuances and sales may occur, could adversely affect the trading price of the Depositary Shares and the market price of our common stock and impair our ability to raise capital through the sale of additional equity securities.

You will have no rights with respect to our common stock until your Depositary Shares are converted, but you may be adversely affected by certain changes made with respect to our common stock.

As a holder of Mandatory Convertible Preferred Stock and/or Depositary Shares, you will have no rights with respect to our common stock, including voting rights, rights to participate in common stock tender offers, if any, and rights to receive dividends or other distributions on our common stock, if any (other than through a conversion rate adjustment), prior to the conversion date with respect to a conversion of your Depositary Shares, but your investment in the Depositary Shares may be negatively affected by these events. Upon conversion, you will be entitled to exercise the rights of a holder of our common stock only as to matters for which the record date occurs after the conversion date. For example, in the event that an amendment is proposed to our Articles of Incorporation requiring stockholder approval and the record date for determining the stockholders of record entitled to vote on the amendment occurs prior to the conversion date, you will not be entitled to vote on the amendment, although you will nevertheless be subject to any changes resulting in the powers, preferences or rights of our common stock. See “Description of Common Stock” in the accompanying prospectus for further discussion of our common stock.

You will have no voting rights except under limited circumstances, and you will need to act through the bank depositary to exercise voting rights with respect to our Mandatory Convertible Preferred Stock.

You will have no voting rights except (i) with respect to certain amendments to the terms of the Mandatory Convertible Preferred Stock, (ii) in the case of certain dividend arrearages, (iii) in certain other limited circumstances and (iv) as specifically required by Missouri law. You will have no right to vote for any members of our board of directors, except upon certain dividend arrearages.

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either as to dividends or the distribution of assets upon liquidation, dissolution or winding-up and having similar voting rights, will be entitled to elect a total of two members of our board of directors, subject to the terms and limitations described in the section of this prospectus supplement entitled “Description of Mandatory Convertible Preferred Stock — Voting Rights.”

In certain circumstances where the rights, preferences, privileges or voting powers of the Mandatory Convertible Preferred Stock are adversely affected thereby, holders of shares of the Mandatory Convertible Preferred Stock will have the right to vote with respect to amendments to our Articles of Incorporation or in connection with reclassifications, mergers or consolidation transactions. See “Description of Mandatory Convertible Preferred Stock — Voting Rights.”

Holders of Depositary Shares must act through the bank depositary to exercise any voting rights in respect of the Mandatory Convertible Preferred Stock. See “Description of Depositary Shares — Voting the Mandatory Convertible Preferred Stock.”

Our ability to declare and pay dividends on the Mandatory Convertible Preferred Stock (and, in turn, on the Depositary Shares) may be limited.

Our declaration and payment of dividends on the Mandatory Convertible Preferred Stock (and, in turn, on the Depositary Shares) in the future will be determined by our board of directors in its sole discretion and will depend on business conditions, our financial condition, earnings and liquidity and other factors. Our ability to declare and pay dividends and make other distributions with respect to our capital stock, including the Mandatory Convertible Preferred Stock, may be restricted by the terms of financing arrangements that we enter into in the future. In the event that the agreements governing any such indebtedness restrict our ability to declare and pay dividends in cash on the shares of Mandatory Convertible Preferred Stock, we may be unable to declare and pay dividends in cash on the shares of Mandatory Convertible Preferred Stock (and, in turn, on the Depositary Shares) unless we can repay or refinance the amounts outstanding under such agreements.

In addition, under Missouri law, our board of directors may only declare and pay dividends on shares of our capital stock at a time when our net assets are not less than (or such dividend payment would not reduce our net assets below) our “stated capital” (which is the sum of the par value of all shares then issued having a par value, plus the consideration received by us for all shares then issued without par value (except as may have been allocated otherwise than to stated capital in a manner permitted by law), plus such other amounts as may have been transferred to our stated capital amount less such formal reductions from said sum as may have been effected in a manner permitted by Missouri law). Further, even if we are permitted under our contractual obligations and Missouri law to declare and pay cash dividends on the shares of Mandatory Convertible Preferred Stock, we may not have sufficient cash to declare and pay dividends in cash on the shares of Mandatory Convertible Preferred Stock (and, in turn, on the Depositary Shares).

If upon (i) mandatory conversion, (ii) an early conversion at the option of a holder or (iii) an early conversion upon a fundamental change, we have not declared all or any portion of the accumulated dividends payable on the Mandatory Convertible Preferred Stock for specified periods, converting holders will receive an additional number of shares of our common stock having a market value generally equal to the amount of such undeclared, accumulated and unpaid dividends, subject to the limitations described under “Description of Mandatory Convertible Preferred Stock — Conversion Rights — Mandatory Conversion,” “Description of Mandatory Convertible Preferred Stock — Conversion Rights — Early Conversion at the Option of the Holder” and “Description of Mandatory Convertible Preferred Stock — Conversion Rights — Early Conversion at the Option of the Holder upon a Fundamental Change,” respectively. In the case of mandatory conversion, early conversion at the option of the holder or conversion upon a fundamental change, if these limits to the adjustment of the conversion rate are reached, we will pay the shortfall in cash to the extent permitted under Missouri law.

You may be subject to U.S. federal income or withholding tax with respect to deemed dividends on the Depositary Shares even though you do not receive a corresponding cash distribution.

The conversion rate of the Mandatory Convertible Preferred Stock and the Depositary Shares is subject to adjustment in certain circumstances. See “Description of Mandatory Convertible Preferred Stock — Conversion

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Rights — Conversion Rate Adjustments.” If, as a result of an adjustment (or failure to make an adjustment), your proportionate interest in our assets or earnings and profits is increased, you may be deemed to have received for U.S. federal income tax purposes a taxable distribution without the receipt of any cash. In addition, we may make distributions to holders of the Mandatory Convertible Preferred Stock and the Depositary Shares that are paid in our common stock, and any such distribution would be taxable to the same extent as a cash distribution of the same amount. In these circumstances and possibly others, you, as a holder of Depositary Shares, may be subject to U.S. federal income tax even though you have received no cash, thus giving rise to an out-of-pocket expense. If you are a non-U.S. holder (as defined in “Material U.S. Federal Income Tax Considerations”), you may be subject to U.S. federal withholding taxes in connection with such a deemed distribution or distribution payable in shares of our common stock. If a broker or other applicable withholding agent pays any withholding taxes on behalf of a non-U.S. holder as a result of a deemed distribution, such withholding agent may set off such payments against cash payments and other distributions otherwise deliverable to the non-U.S. holder (or other assets of the non-U.S. holder held by such withholding agent). See “Material U.S. Federal Income Tax Considerations” for a further discussion of U.S. federal income tax considerations with respect to the Mandatory Convertible Preferred Stock and the Depositary Shares. In addition, the Department of the Treasury and the Internal Revenue Service recently published proposed Treasury regulations that, if finalized, may affect holders deemed to receive such a distribution. You should consult your tax advisors regarding the effect, if any, of the proposed Treasury regulations in your particular circumstances.

We have not determined whether we are a U.S. real property holding corporation.

We have not determined whether we are a U.S. real property holding corporation (“USRPHC”) within the meaning of the Foreign Investment in Real Property Tax Act (“FIRPTA”). We can give no assurance that we are not or will not become one in the future. If we are or become a USRPHC, so long as the Depositary Shares (which represent Mandatory Convertible Preferred Stock) or our common stock is “regularly traded on an established securities market,” a non-U.S. holder will be subject to U.S. federal net income tax on a disposition of such regularly traded stock (including, in certain circumstances, gain realized upon the conversion of Mandatory Convertible Preferred Stock) only if the non-U.S. holder actually or constructively holds or held (at any time during the shorter of the five-year period preceding the date of disposition or the non-U.S. holder’s holding period) more than 5% of such class of stock. Although not free from doubt, we anticipate that the Depositary Shares (which represent Mandatory Convertible Preferred Stock) will be “regularly traded on an established securities market.” However, if our Mandatory Convertible Preferred Stock is not treated as so traded, gain arising from the sale or other taxable disposition of such stock by a non-U.S. holder will not be subject to U.S. federal income taxation as a sale of a “United States real property interest,” or “USRPI,” if our common stock is part of a class of stock that is “regularly traded” on an established securities market and the non-U.S. holder has not, at the time such non-U.S. holder acquires the Mandatory Convertible Preferred Stock and at certain other times described in the applicable Treasury Regulations, directly or indirectly, held Mandatory Convertible Preferred Stock (and in certain cases other direct or indirect interests in our stock) that had a fair market value in excess of 5% of the fair market value of all of our outstanding common stock. We believe that our common stock is and anticipate it will continue to be “regularly traded” on an established securities market. If gain on the sale or other taxable disposition of our stock were subject to taxation under FIRPTA, the non-U.S. holder would be subject to U.S. federal income tax on the gain realized on a disposition of the Depositary Shares, Mandatory Convertible Preferred Stock or our common stock, generally would be required to file a U.S. federal income tax return and (and, if the relevant securities were not then publicly traded, and certain other conditions were met) a 15% withholding tax would apply to the gross proceeds from such sale. Also, distributions that are treated as return of capital or gain could be subject to withholding tax at a rate of 15% under FIRPTA if we are considered a USRPHC and our stock is not “regularly traded” on an established securities market. See “Material U.S. Federal Income Tax Considerations – Tax Consequences Applicable to Non-U.S. Holders.” Non-U.S. holders should consult their own tax advisors about the consequences that could result if we are, or become, a USRPHC.

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Certain rights of the holders of the Mandatory Convertible Preferred Stock, the Depositary Shares and the Series A Preferred (if issued) and certain contractual and statutory provisions could delay or prevent an otherwise beneficial takeover or takeover attempt of us and, therefore, the ability of holders of Depositary Shares to exercise their rights associated with a potential fundamental change.

Certain rights of the holders of the Mandatory Convertible Preferred Stock, the Depositary Shares and the Series A Preferred, if issued, could make it more difficult or more expensive for a third party to acquire us. For example, if a fundamental change were to occur on or prior to the mandatory conversion date, holders of the Depositary Shares and holders of the Series A Preferred, if issued, may have the right to cause the conversion of their Depositary Shares (and, in turn, the Mandatory Convertible Preferred Stock) or convert their Series A Preferred, respectively, in whole or in part, at an increased conversion rate and will also be entitled to receive a fundamental change dividend make-whole amount equal to the present value of all remaining dividend payments on the Mandatory Convertible Preferred Stock represented by the Depositary Shares or the Series A Preferred so converted, as the case may be. See “Description of Mandatory Convertible Preferred Stock — Conversion Rights — Early Conversion at the Option of the Holder upon a Fundamental Change” with respect to the Mandatory Convertible Preferred Stock. These features of the Depositary Shares and the Mandatory Convertible Preferred Stock and of the Series A Preferred, if issued, could increase the cost of acquiring us or otherwise discourage a third party from acquiring us or removing incumbent management.

In addition, provisions of Missouri law and our Articles of Incorporation could make it more difficult for a third party to acquire control of us or have the effect of discouraging a third party from attempting to acquire control of us. See “Description of Common Stock” in the accompanying prospectus.

An active trading market for the Depositary Shares does not exist and may not develop.

The Depositary Shares are a new issue of securities with no established trading market. We intend to apply to have the Depositary Shares listed on the NYSE under the symbol “GXPPRB,” and if the application is approved, we expect trading to commence within 30 days of the first original issuance date of the Depositary Shares. Even if the Depositary Shares are approved for listing on the NYSE, such listing does not guarantee that a trading market for the Depositary Shares will develop or, if a trading market for the Depositary Shares does develop, the depth or liquidity of that market or the ability of the holders to sell the Depositary Shares or to sell the Depositary Shares at a favorable price.

The trading price of our common stock will directly affect the trading price of the Depositary Shares.

The trading price of the Depositary Shares will be directly affected by, among other things, the trading price of our common stock. It is impossible to predict whether the price of our common stock will rise or fall. Our operating results, prospects and economic, financial, political and other factors will affect trading prices of our common stock and the Depositary Shares, as will future issuances of our common stock. In addition, market conditions can affect the capital markets generally, thereby affecting the price of our common stock. These conditions may include the level of, and fluctuations in, the trading prices of stocks generally and sales of substantial amounts of our common stock in the market after this offering of the Depositary Shares or the perception that such sales could occur. See “— The price of the Depositary Shares and our common stock may be volatile. This volatility may affect the price at which you could sell the Depositary Shares or our common stock, and the sale of substantial amounts of our common stock could adversely affect the price of our common stock.”

Additionally, fluctuations in interest rates may give rise to arbitrage opportunities based upon changes in the relative value of the Depositary Shares and the common stock underlying the Mandatory Convertible Preferred Stock represented by the Depositary Shares. In addition, the issuance of the Depositary Shares and the Series A Preferred, if issued, may result in hedging activity by holders of the Depositary Shares and the Series A Preferred that view such Depositary Shares or Series A Preferred, as the case may be, as a more attractive means of equity participation in us than a direct investment in our common stock. This arbitrage and hedging could, in turn, negatively affect the trading prices of the Depositary Shares and our common stock.

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The Series A Preferred (if issued) will rank on a parity with the Mandatory Convertible Preferred Stock represented by the Depositary Shares as to dividend payments and liquidation preference, and we may issue additional series of preferred or preference stock that rank on a parity with the Mandatory Convertible Preferred Stock as to dividend payments and liquidation preference and that vote with the Mandatory Convertible Preferred Stock on matters relating to preferred directors, which may negatively affect your investment.

Without giving effect to the shares of Mandatory Convertible Preferred Stock represented by the Depositary Shares that we are offering hereby or to the shares of Series A Preferred that we expect to issue privately in connection with the Merger, we have the authority under our Articles of Incorporation to issue 11,000,000 shares of preference stock, without par value. Our Articles of Incorporation do not prohibit us from issuing additional series of preferred or preference stock that would rank on a parity with the Mandatory Convertible Preferred Stock and the Series A Preferred as to dividends and the distribution of assets upon liquidation, dissolution or winding up and that would vote together with the Mandatory Convertible Preferred Stock as to matters relating to preferred directors, as described under “Description of Mandatory Convertible Preferred Stock — Voting Rights — Preferred Directors.” The planned issuance of the Series A Preferred in connection with the Merger, and the issuance of any additional series of preferred or preference stock, could have the effect of reducing the amounts available to the holders of the Mandatory Convertible Preferred Stock (and, accordingly, to holders of the Depositary Shares) in the event of our liquidation. If we do not have sufficient funds to pay dividends on the outstanding Mandatory Convertible Preferred Stock, the Series A Preferred, if issued, and such other series of preferred or preference stock, it would also reduce amounts available to the holders of the Mandatory Convertible Preferred Stock (and, accordingly, to holders of the Depositary Shares) for the payment of dividends. The interests of the holders of any other series of preferred or preference stock that we issue may be different from the interests of the holders of the Mandatory Convertible Preferred Stock.

The Depositary Shares and the Series A Preferred, if issued, may adversely affect the market price of our common stock.

The market price of our common stock is likely to be influenced by the Depositary Shares and the Series A Preferred, if issued. For example, the market price of our common stock could become more volatile and could be depressed by:

Our shares of common stock will rank junior to the Mandatory Convertible Preferred Stock represented by the Depositary Shares and both equity securities will rank junior to all of our consolidated liabilities.

In the event of a bankruptcy, liquidation, dissolution or winding up, our assets will be available to pay obligations on the Mandatory Convertible Preferred Stock represented by the Depositary Shares and our common stock only after all of our consolidated liabilities have been paid. In the event of a bankruptcy, liquidation, dissolution or winding up, there may not be sufficient assets remaining, after paying our and our subsidiaries’ liabilities, to pay any amounts with respect to the Mandatory Convertible Preferred Stock, the Series A Preferred, if issued, and our common stock then outstanding. Additionally, no distribution of our assets may be made to holders of our common stock until we have paid to holders of the Mandatory Convertible Preferred Stock and of the Series A Preferred, if issued, a liquidation preference equal to $1,000 per share plus accumulated and unpaid dividends. We have a significant amount of indebtedness, which amounted to approximately $4.3 billion at June 30, 2016. We expect to incur additional indebtedness to fund the Merger and to issue the Series A Preferred in connection with the closing of the Merger. As of June 30, 2016, on a pro forma basis to give effect to the Merger

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and the other events described under “Prospectus Supplement Summary — Summary Historical and Pro Forma Financial Information — Summary Unaudited Pro Forma Financial Information,” our total indebtedness would have been approximately $13.0 billion including approximately $0.4 billion of currently payable long-term debt, approximately $0.8 billion of short-term borrowings and approximately $11.8 billion of long-term debt and other long-term obligations.

Certain provisions of the General and Business Corporation Law of Missouri, our Articles of Incorporation and our Bylaws may delay, hinder or prevent a change of control in us, which could have an adverse effect on the market price of our common stock and the Depositary Shares.

Provisions of the General and Business Corporation Law of Missouri and our Articles of Incorporation and Bylaws could delay or discourage some transactions involving an actual or potential change in control of us or our management and may limit the ability of our stockholders to remove current management or approve transactions that our stockholders may deem to be in their best interests. These provisions may also make it difficult and expensive for a third party to pursue a tender offer, change in control or takeover attempt of us that is opposed by our management or our board of directors. Stockholders who might desire to participate in those types of transactions may not have an opportunity to do so, even if the transaction is favorable to the stockholders. These anti-takeover provisions could substantially impede the ability of public stockholders to benefit from a change in control or change our management or our board of directors and, as a result, may adversely affect the market price of our common stock and the Depositary Shares and the ability of stockholders to realize any potential change of control premium.

We may be unable to, or may choose not to, continue to pay dividends on our common stock at current rates or at all.

Any future payments of cash dividends will depend on our financial condition, our capital requirements and earnings, and the ability of our operating subsidiaries to distribute cash to us, as well as other factors that our board of directors may consider.

The price of the Depositary Shares and our common stock may be volatile. This volatility may affect the price at which you could sell the Depositary Shares or our common stock, and the sale of substantial amounts of our common stock could adversely affect the price of our common stock.

The market price for our common stock has historically experienced, and may continue to experience, volatility. This volatility may affect the price at which you could sell the Depositary Shares or our common stock, and the sale of substantial amounts of our common stock could adversely affect the price of the Depositary Shares or our common stock. Our stock price may continue to be volatile and subject to significant price and volume fluctuations in response to market and other factors, including: the other risk factors discussed in the documents incorporated by reference herein; variations in our quarterly operating results from our securities analysts’ or investors’ expectations; downward revisions in securities analysts’ estimates; and announcement by us or our competitors of significant acquisitions, joint ventures, capital commitments or other material developments.

In addition, the sale or availability for sale of substantial amounts of our common stock could adversely impact its price. We have agreed to issue our Series A Preferred, subject to certain conditions, which is expected to be issued upon the consummation of the Merger and will be mandatorily convertible into an aggregate of up to 26,176,950 shares of our common stock, subject to anti-dilution, make-whole and other adjustments, which will cause our existing shareholders’ ownership to be diluted. Also, concurrently with this offering, we are offering, by means of a separate prospectus supplement, 52,600,000 shares of our common stock (or 60,490,000 shares if the underwriters of that offering exercise in full their option to purchase additional shares). The shares of our common stock will also cause our existing shareholders’ ownership to be diluted. See “Prospectus Supplement Summary — Recent Developments — Pending Westar Merger” and “Concurrent Offering of Common Stock.”

As of September 26, 2016, we had outstanding approximately 154,795,018 shares of our common stock. We also had outstanding approximately 625,100 performance shares as of September 26, 2016, under which up to 1,250,200 shares of common stock could be issued, depending upon achievement of specified goals, and approximately 127,105 director deferred share units.

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We expect that we will need to raise additional capital, and raising additional funds by issuing additional equity securities or with additional debt financing may cause dilution to existing stockholders or restrict our operations.

We expect that we will need to raise additional capital in the future, including the additional equity and debt securities planned to finance the Merger. See “— Recent Developments — Sources and Uses.” We may raise additional funds through public or private equity or debt offerings or other financings. Additional issuance of equity securities, including securities that are convertible into or exchangeable for, or that represent the right to receive, common stock, could dilute the value of shares of our common stock and cause the market price of our common stock to decline, including by:

Any new debt financing we enter into may involve covenants that restrict our operations more than our current outstanding debt and credit facilities. These restrictive covenants could include limitations on additional borrowings, specific restrictions on the use of our assets as well as prohibitions or limitations on our ability to create liens, pay dividends, receive distributions from our subsidiaries, redeem our stock or make investments. These factors could hinder our access to capital markets and limit or delay our ability to carry out our capital expenditure program.

USE OF PROCEEDS

We estimate that we will receive net proceeds from our sale of the Depositary Shares in this offering, after deducting the underwriting discount and estimated offering expenses, to be approximately $            (or approximately $        if the underwriters of this offering exercise in full their option to purchase additional Depositary Shares).

In addition, we expect to receive net proceeds, after deducting the underwriting discount and estimated offering expenses, of approximately $        million from the concurrent offering (or approximately $        if the underwriters of that offering exercise in full their option to purchase additional shares of common stock).

We intend to use the net proceeds from both of these offerings to finance a portion of the Cash Consideration for the Merger. See “Prospectus Supplement Summary — Recent Developments — Pending Westar Merger” and “— Sources and Uses.” Pending any specific application, we may use a portion of the net proceeds to repay short-term indebtedness associated with transaction expenses related to the Merger, deposit proceeds in our FERC-approved money pool and invest in short-term marketable securities. As of September 26, 2016, our outstanding short-term indebtedness, including current maturities of long-term debt, was approximately $853.6 million with a weighted average interest rate of approximately 3.25%.

This offering of the Depositary Shares is not contingent upon the concurrent offering, and the concurrent offering is not contingent upon the offering of the Depositary Shares hereunder. Neither this offering nor the concurrent offering is conditioned on the consummation of the Merger, and there can be no assurance that the Merger will be consummated on the terms described herein or at all. If the Merger is not consummated, we intend to use the net proceeds of this offering and the net proceeds of the concurrent offering, net of certain fees and expenses and net of the aggregate redemption amount paid in cash if we choose to exercise our acquisition termination option to redeem all of the Mandatory Convertible Preferred Stock and thereby all of the Depositary Shares offered hereby, pay fees under the Merger Agreement, if any, and for general corporate purposes, which may include debt repayment or capital expenditures.

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CAPITALIZATION AND SHORT-TERM DEBT

The following table sets forth our consolidated capitalization and short-term debt as of June 30, 2016:

Because the closing of this offering of the Depositary Shares is not contingent upon the closing of the concurrent offering or the completion of the Merger, you should not assume that the sale of our common stock, as reflected in the second column below, or the other Merger-related financings, as reflected in the third column below, will take place. See “Concurrent Offering of Common Stock” in this prospectus supplement. This table should be read in conjunction with our consolidated financial statements and related notes incorporated by reference in this prospectus supplement and the accompanying prospectus. See “Where You Can Find More Information” in this prospectus supplement.

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PRICE RANGE OF COMMON STOCK AND DIVIDENDS

Our common stock is listed on the NYSE under the symbol “GXP.” The following table sets forth the high and low sale prices, as reported in the consolidated transaction reporting system and adjusted for historical stock dividends and dividends declared per share of our common stock. As of September 26, 2016, there were 154,795,018 shares of our common stock outstanding.

On September 26, 2016, the last reported sale price of our common stock in the consolidated transaction reporting system was $27.94. As of September 26, 2016, there were approximately 15,192 holders of record of our common stock.

In August 2016, our board of directors declared a dividend of $0.2625 per share payable on September 20, 2016 to shareholders of record as of August 29, 2016.

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DESCRIPTION OF MANDATORY CONVERTIBLE PREFERRED STOCK

The following is a summary of the material terms of the Mandatory Convertible Preferred Stock. This summary is not complete. The following summary of the terms and provisions of the Mandatory Convertible Preferred Stock is qualified in its entirety by reference to the certificate of designations setting forth the terms of the Mandatory Convertible Preferred Stock (the “Certificate of Designations”) as well as our Articles of Incorporation, copies of which will be available upon request at the address set forth in the section of this prospectus supplement entitled “Where You Can Find More Information.”

The bank depositary will initially be the sole holder of the Mandatory Convertible Preferred Stock. However, the holders of Depositary Shares will be entitled, through the bank depositary, to exercise the rights, preferences, privileges and voting powers of holders of the Mandatory Convertible Preferred Stock, subject to the terms of the deposit agreement and as described herein under “Description of Depositary Shares.” Each Depositary Share represents a 1/20th interest in a share of the Mandatory Convertible Preferred Stock.

As used in this section, unless otherwise expressly stated or the context otherwise requires, the terms “Great Plains Energy Incorporated,” “the Company,” “us,” “we” or “our” refer to Great Plains Energy Incorporated and not any of its subsidiaries.

General

Subject to the provisions of our Articles of Incorporation, as heretofore amended, and the limitations prescribed by law, our Articles of Incorporation authorizes our board of directors to issue up to 11,000,000 shares of preference stock, without par value, in one or more series, with such voting powers, full or limited, or no voting powers and such designations, preferences and relative, participating, optional and other special rights, and the qualifications, limitations or restrictions, as shall be stated and expressed in the resolutions providing for the issuance. The designations, powers, preferences and other rights, and the qualifications, limitations and restrictions shall be set forth in the Certificate of Designations, which will be filed with the Secretary of State of Missouri. As of the date of this prospectus supplement, no shares of preference stock are outstanding. However, we expect to issue privately upon consummation of the Merger 750,000 shares of our preference stock to be designated “Series A Mandatory Convertible Preferred Stock.” See “Prospectus Supplement Summary — Recent Developments — Preferred Stock Purchase Agreement.” At the consummation of this offering, we will issue 750,000 shares of our preference stock to be designated “Series B Mandatory Convertible Preferred Stock” (which we refer to as the Mandatory Convertible Preferred Stock) in the form of 15,000,000 Depositary Shares. In addition, we have granted the underwriters an option to purchase up to 112,500 additional shares of the Mandatory Convertible Preferred Stock in the form of 2,250,000 Depositary Shares, as described under “Underwriting.”

When issued, the Mandatory Convertible Preferred Stock and our common stock issuable upon the conversion of the Mandatory Convertible Preferred Stock will be fully paid and non-assessable. The holders of the Mandatory Convertible Preferred Stock and our common stock issued upon conversion of the Mandatory Convertible Preferred Stock will have no pre-emptive or preferential right to purchase or subscribe to our stock, obligations, warrants or other securities of any class.

We do not intend to apply to list the Mandatory Convertible Preferred Stock on any securities exchange or any automated dealer quotation system, but we do intend to apply to list the Depositary Shares on the NYSE as described under “Description of Depositary Shares — Listing.”

The transfer agent, registrar, conversion and dividend disbursing agent for shares of the Mandatory Convertible Preferred Stock and the transfer agent and registrar for shares of our common stock is Computershare Trust Company, N.A.

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Ranking

The Mandatory Convertible Preferred Stock, with respect to dividend rights and the rights to distribution of assets upon our liquidation, winding-up or dissolution, will rank:

In addition, the Mandatory Convertible Preferred Stock, with respect to dividend rights or rights to distribution of assets upon our liquidation, winding-up or dissolution, will be structurally subordinated to existing and future indebtedness of our subsidiaries. As of June 30, 2016, on a pro forma basis to give effect to the Merger and the other events described under “Prospectus Supplement Summary — Summary Historical and Pro Forma Financial Information — Summary Unaudited Pro Forma Financial Information,” our total indebtedness would have been approximately $13.0 billion, including approximately $0.4 billion of currently payable long-term debt, approximately $0.8 billion of short-term borrowings and approximately $11.8 billion of long-term debt and other long-term obligations.

Dividends

Subject to the rights of holders of any class or series of our capital stock ranking senior to the Mandatory Convertible Preferred Stock with respect to dividends, holders of shares of the Mandatory Convertible Preferred Stock will be entitled to receive, when, as and if declared by our board of directors or an authorized committee of our board of directors and to the extent permitted under Missouri law, cumulative dividends at an annual rate of     % of the liquidation preference of $1,000 per share of Mandatory Convertible Preferred Stock (equivalent to $        per year per share). We will pay such dividends in cash, by delivery of shares of our common stock or by payment or delivery, as the case may be, of any combination of cash and our common stock, at our election, as described under “— Method of Payment of Dividends” below. If declared, dividends on the Mandatory Convertible Preferred Stock will be payable quarterly on March 15, June 15, September 15 and December 15 of each year, commencing on December 15, 2016 and ending on, and including, the mandatory conversion date (each, a “dividend payment date”), at such annual rate, and shall accumulate from the most recent date as to which dividends shall have been paid or, if no dividends have been paid, from the issue date of the Mandatory Convertible Preferred Stock, whether or not in any dividend period or periods there have been funds or stock lawfully available under Missouri law for the payment of such dividends. If a dividend payment date falls on any day other than a business day, declared dividends for such dividend payment date will be payable on the first business day immediately following such dividend payment date. A “dividend period” refers to a period commencing on, and including, a dividend payment date (or if no dividend payment date has occurred, commencing on, and including, the issue date), and ending on, and including, the day immediately preceding the next succeeding dividend payment date.

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A “business day” means any day other than a Saturday or Sunday or other day on which commercial banks in New York City are authorized or required by law or executive order to close. Any accumulated and unpaid dividends from any preceding dividend period can be declared and paid on a date determined by our board of directors or an authorized committee of our board of directors in its good faith.

Dividends will be payable to holders of record as they appear on our stock register at 5:00 p.m., New York City time, on the first calendar day of the month in which such dividend payment date falls or such other record date fixed by our board of directors or any duly authorized committee thereof that is not more than 60 nor less than 20 calendar days prior to such dividend payment date, but only to the extent a dividend has been declared to be payable on such dividend payment date (each, a “regular record date”), except that dividends payable on the mandatory conversion date, as defined below, will be payable to the holders presenting the Mandatory Convertible Preferred Stock for conversion. The regular record date shall apply regardless of whether it is a business day.

Dividends payable on the Mandatory Convertible Preferred Stock for each full dividend period will be computed by dividing the annual dividend rate by four. Dividends payable on the Mandatory Convertible Preferred Stock for any period other than a full dividend period will be based upon the actual number of days elapsed during the period and computed on the basis of a 360-day year consisting of twelve 30-day months. The initial dividend on the Mandatory Convertible Preferred Stock for the first dividend period, assuming the issue date is October     , 2016, is expected to be $        per share (based on the annual dividend rate of     % and a liquidation preference of $1,000 per share) and will be payable, if declared, on December 15, 2016 to the holders of record thereof on December 1, 2016. Each subsequent quarterly dividend on the Mandatory Convertible Preferred Stock, when, as and if declared, will be $        per share (based on the annual dividend rate of     % and a liquidation preference of $1,000 per share). Accumulated dividends on shares of Mandatory Convertible Preferred Stock will not bear interest if they are paid subsequent to the applicable dividend payment date.

No dividend will be declared or paid upon, or any sum of cash or number of shares of our common stock set apart for the payment of dividends upon, any outstanding shares of Mandatory Convertible Preferred Stock with respect to any dividend period unless all dividends for all preceding dividend periods have been declared and paid, or declared and a sum of cash or number of shares sufficient for the payment thereof has been set apart for the payment of such dividends, upon all outstanding shares of the Mandatory Convertible Preferred Stock.

No dividend will be paid upon any outstanding shares of Mandatory Convertible Preferred Stock unless and until our board of directors, or an authorized committee of our board of directors, declares a dividend payable with respect to the Mandatory Convertible Preferred Stock. Our ability to declare and pay dividends and make other distributions with respect to our capital stock, including the Mandatory Convertible Preferred Stock, may be restricted by the terms of financing arrangements that we enter into in the future. In addition, our ability to declare and pay dividends may be limited by applicable Missouri law. See “Risk Factors — Risks Related to the Depositary Shares, the Mandatory Convertible Preferred Stock, Our Common Stock and This Offering — Our ability to declare and pay dividends on the Mandatory Convertible Preferred Stock (and, in turn, on the Depositary Shares) may be limited.”

Method of Payment of Dividends

Subject to the limitations described below, we may pay any declared dividend (or any portion of any declared dividend) on the Mandatory Convertible Preferred Stock (whether or not for a current dividend period or any prior dividend period), including in connection with the payment of declared and unpaid dividends pursuant to the provisions described under “— Conversion Rights — Mandatory Conversion,” “— Conversion Rights — Early Conversion at the Option of the Holder,” and “— Conversion Rights — Early Conversion at the Option of the Holder upon a Fundamental Change,” determined in our good faith:

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provided that in the case of conversion upon and following a fundamental change that is a reorganization event (as defined below), dividends otherwise payable in shares of our common stock may be paid by delivery of units of exchange property, as described under “— Recapitalizations, Reclassifications and Changes of Our Common Stock”; provided further that if our board of directors cannot lawfully authorize payment of all or any portion of such accumulated and unpaid dividends in cash under Missouri law, it shall authorize payment of such dividends in shares of our common stock or units of exchange property, as the case may be, to the extent permitted under Missouri law.

We will make each payment of a declared dividend on shares of the Mandatory Convertible Preferred Stock in cash, except to the extent we elect to make all or any portion of such payment in shares of our common stock.

We will give holders of the Mandatory Convertible Preferred Stock notice of any such election, as well as the portion of such payment that will be made in cash and the portion that will be made in shares of our common stock, no later than 10 scheduled trading days (as defined below) prior to the dividend payment date for such dividend; provided that if we do not provide timely notice of this election, we will be deemed to have elected to pay the relevant dividend in solely cash. If we elect to make any such payment of a declared dividend, or any portion thereof, in shares of our common stock, such shares shall be valued for such purpose, in the case of any dividend payment or portion thereof, at 97% of the average VWAP per share of our common stock over the five consecutive trading day (as defined below) period commencing on, and including, the seventh scheduled trading day prior to the applicable dividend payment date (the “dividend payment average price”). If the relevant dividend payment date occurs on or prior to the last trading day of such five consecutive trading day period, delivery of the shares of our common stock owed in respect of the dividend due on such dividend payment date shall be deferred until the business day immediately following the last trading day of such five consecutive trading day period.

However, in no event will the number of shares of our common stock delivered in connection with any declared dividend, including any declared dividend payable in connection with a conversion, exceed a number equal to the total dividend payment divided by $        , which amount represents approximately 35% of the initial price (as defined below), subject to adjustment in a manner inversely proportional to any anti-dilution adjustment to each fixed conversion rate (such dollar amount, as adjusted, the “floor price”). To the extent that the amount of the declared dividend as to which we have elected to deliver shares of our common stock in lieu of paying cash exceeds the product of the number of shares of our common stock delivered in connection with such declared dividend and 97% of the dividend payment average price with respect to the dividend payment date falling on September 15, 2019, we will, to the extent permitted under Missouri law, pay such excess amount in cash, and any amounts not so paid will continue to be owed by us as accumulated and unpaid dividends.

No fractional shares of our common stock will be delivered to holders of the Mandatory Convertible Preferred Stock in payment or partial payment of a dividend. We will instead pay a cash adjustment (computed to the nearest cent) based on the dividend payment average price with respect to such dividend.

To the extent we determine in our reasonable judgment that a shelf registration statement is required in connection with the issuance of, or for resales of, shares of our common stock issued as payment of a dividend on the shares of Mandatory Convertible Preferred Stock, to (or by) holders thereof that are not “affiliates” of ours (or were not our “affiliates” during the immediately preceding three months) for purposes of the Securities Act, including dividends paid in connection with a conversion, we will, to the extent such a registration statement is not currently filed and effective, if we determine to issue such shares of common stock, use our reasonable best efforts to file and maintain the effectiveness of such a shelf registration statement until the earlier of such time as all such shares of common stock have been resold thereunder and such time as all such shares would be freely tradable pursuant to Rule 144 under the Securities Act without registration. To the extent applicable, we will also use our reasonable best efforts to have such shares of common stock qualified or registered under applicable state securities laws, if required, and approved for listing on the NYSE (or if shares of our common stock are not listed on the NYSE, on the principal other U.S. national securities exchange on which shares of our common stock are then listed).

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Definitions

For purposes of this “Description of Mandatory Convertible Preferred Stock” section, the following terms have the meanings set forth below:

“VWAP” per share of our common stock on any trading day means such price per share as displayed under the heading “Bloomberg VWAP” on Bloomberg (or any successor service) page GXP <Equity> AQR (or its equivalent successor if such page is not available) in respect of the period from the scheduled open to 4:00 p.m., New York City time, on such trading day; or, if such price is not available, the market value per share of our common stock on such trading day as determined, using a volume-weighted average method, by a nationally recognized independent investment banking firm retained by us for this purpose. The “average VWAP” means, for any period, the arithmetic average of the VWAP for each trading day in such period.

A “trading day” is any day on which:

A “market disruption event” means any of the following events:

For purposes of the first two bullets of the definition of “market disruption event” above, the relevant exchange or quotation system will be the NYSE; provided that if our common stock (or any other security into which the Mandatory Convertible Preferred Stock becomes convertible in connection with any reorganization event) is not listed on the NYSE, such relevant exchange or quotation system will be the principal other U.S. national securities exchange on which shares of our common stock are (or such other security is) then listed.

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A “scheduled trading day” is any day that is scheduled to be a trading day, except that if our common stock is not listed on a national securities exchange, “scheduled trading day” means a business day.

Dividend Stopper

So long as any share of Mandatory Convertible Preferred Stock remains outstanding:

in each case, unless all accumulated and unpaid dividends for all past dividend periods, including the latest completed dividend period, on all outstanding shares of the Mandatory Convertible Preferred Stock have been or are contemporaneously declared and paid in full (or have been declared and a sufficient sum of cash and/or number of shares of our common stock for the payment thereof has been set aside for the benefit of the holders of shares of the Mandatory Convertible Preferred Stock on the applicable regular record date).

The limitations on distributions described in the immediately preceding paragraph will not apply to:

“Share dilution amount” means the increase in the number of diluted shares outstanding (determined in accordance with generally accepted accounting principles in the United States, and as measured from the date of our consolidated financial statements most recently filed with the SEC prior to the issue date) resulting from the grant, vesting or exercise of equity-based compensation to employees, directors or consultants and equitably adjusted for any stock split, stock dividend, reverse stock split, reclassification or similar transaction.

When dividends are not paid (or declared and a sufficient sum of cash and/or number of shares of our common stock for payment thereof set aside for the benefit of the holders thereof on the applicable regular record date) on any dividend payment date (or, in the case of parity stock having dividend payment dates different from such dividend payment dates, on a dividend payment date falling within a dividend period related to such dividend payment date) in full upon the Mandatory Convertible Preferred Stock and any shares of parity stock, all dividends declared on the Mandatory Convertible Preferred Stock and all such parity stock and payable on such dividend payment date (or, in the case of parity stock having dividend payment dates different from such dividend payment dates, on a dividend payment date falling within a dividend period related to such dividend payment date) shall be declared and paid pro rata so that the respective amounts of such dividends declared shall bear the same ratio to each other as all accumulated and unpaid dividends per share on the shares of the Mandatory Convertible Preferred Stock and all parity stock payable on such dividend payment date (or, in the

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case of parity stock having dividend payment dates different from such dividend payment dates, on a dividend payment date falling within a dividend period related to such dividend payment date) (subject to their having been declared by our board of directors or a duly authorized committee of our board of directors out of funds lawfully available under Missouri law and including, in the case of parity stock that bears cumulative dividends, all accumulated but unpaid dividends) bear to each other. If our board of directors or a duly authorized committee of our board of directors determines not to pay any dividend or a full dividend on a dividend payment date, we will provide 20 calendar days’ written notice to the holders of the Mandatory Convertible Preferred Stock prior to such dividend payment date, or as reasonably practicable thereafter.

Subject to the foregoing, dividends (payable in cash, securities or other property) as may be determined by our board of directors or any duly authorized committee of our board of directors may be declared and paid on any securities, including our common stock and other junior stock, from time to time out of any funds lawfully available under Missouri law for such payment, and holders of the Mandatory Convertible Preferred Stock will not be entitled to participate in any such dividends. Unless otherwise agreed by holders of a majority in voting power of the shares of Mandatory Convertible Preferred Stock at the time outstanding, payments to holders of parity stock will be made in the same proportion of cash and shares of our common stock that are paid to holders of the Mandatory Convertible Preferred Stock.

Acquisition Termination Redemption

We expect to use the net proceeds from this offering in connection with the Merger as described under “Prospectus Supplement Summary — Recent Developments — Pending Westar Merger.” Within ten business days following the earlier of (a) the date on which an acquisition termination event (as defined below) occurs and (b) 5:00 p.m. (New York City time) on November 30, 2017, if the Merger has not closed on or prior to such time on such date, we will be entitled, but not required, in our sole discretion, to mail a notice of an acquisition termination redemption to holders of the Mandatory Convertible Preferred Stock (provided that, if the Mandatory Convertible Preferred Stock are held in book-entry form through DTC, we may give such notice in any manner permitted by DTC). If we provide notice of an acquisition termination redemption to holders of the Mandatory Convertible Preferred Stock, then, on the acquisition termination redemption date (as defined below), we will be required to redeem the Mandatory Convertible Preferred Stock, in whole but not in part, at a redemption amount per share equal to the acquisition termination make-whole amount (as defined below).

“Acquisition termination event” means either (1) the Merger is terminated or (2) we determine in our reasonable judgment that the Merger will not occur.

“Acquisition termination make-whole amount” means, for each share of Mandatory Convertible Preferred Stock, an amount in cash equal to $1,000 plus accumulated and unpaid dividends to, but excluding, the acquisition termination redemption date (whether or not declared); provided, however, that if the acquisition termination share price (as defined below) exceeds the initial price (as defined below), the acquisition termination make-whole amount will equal the reference amount (as defined below).

“Acquisition termination share price” means the average VWAP per share of our common stock over the 10 consecutive trading day period ending on, and including, the trading day immediately preceding the date on which we provide notice of an acquisition termination redemption.

The “reference amount” means, for each share of Mandatory Convertible Preferred Stock, an amount equal to the sum of the following amounts:

(i) a number of shares of our common stock equal to the acquisition termination conversion rate (as defined below); plus

(ii) cash in an amount equal to the acquisition termination dividend amount (as defined below);

provided that we may pay cash in lieu of delivering all or any portion of the shares of our common stock set forth in clause (i) above, and we may deliver shares of our common stock in lieu of paying all or any portion of the cash amount set forth in clause (ii) above, in each case, as described below.

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“Acquisition termination conversion rate” means a rate equal to the fundamental change conversion rate assuming for such purpose that the date on which we provide notice of an acquisition termination redemption is the fundamental change effective date (as defined below) and that the fundamental change share price is the acquisition termination share price.

“Acquisition termination dividend amount” means an amount of cash equal to the sum of (x) the fundamental change dividend make-whole amount and (y) the accumulated dividend amount, assuming, in each case, for such purpose that the date on which we provide notice of acquisition termination redemption is the fundamental change effective date.

For a description of the terms (i) fundamental change conversion rate, fundamental change dividend make-whole amount, accumulated dividend amount and fundamental change share price, see “— Conversion Rights —Early Conversion at the Option of the Holder upon a Fundamental Change” and (ii) initial price, see “—Conversion Rights — Mandatory Conversion.”

If the acquisition termination share price exceeds the initial price, we may pay cash (computed to the nearest cent) in lieu of delivering all or any portion of the number of shares of our common stock equal to the acquisition termination conversion rate. If we make such an election, we will deliver cash (computed to the nearest cent) in an amount equal to such number of shares of our common stock in respect of which we have made this election, multiplied by the acquisition termination market value.

In addition, if the acquisition termination share price exceeds the initial price, we may deliver shares of our common stock in lieu of paying cash for some or all of the acquisition termination dividend amount. If we make such an election, we will deliver a number of shares of our common stock equal to such portion of the acquisition termination dividend amount to be paid in shares of our common stock, divided by the greater of (i) the floor price and (ii) 97% of the acquisition termination market value; provided that, if the acquisition termination dividend amount or portion thereof in respect of which shares of our common stock are delivered exceeds the product of such number of shares of our common stock multiplied by 97% of the acquisition termination market value, we will, to the extent permitted under Missouri law, declare and pay such excess amount in cash (computed to the nearest cent).

“Acquisition termination market value” means the average VWAP per share of our common stock over the 20 consecutive trading day period commencing on, and including, the third trading day following the date on which we provide notice of an acquisition termination redemption.

“Acquisition termination redemption date” means the date specified by us in our notice of acquisition termination redemption that is not less than 30 nor more than 60 calendar days following the date on which we provide notice of such acquisition termination redemption; provided that if (a) the acquisition termination share price is greater than the initial price and (b)(i) we elect to pay cash in lieu of delivering all or any portion of the shares of our common stock equal to the acquisition termination conversion rate or (ii) we elect to deliver shares of our common stock in lieu of paying all or any portion of the acquisition termination dividend amount in cash, then the acquisition termination redemption date will be also not earlier than the third business day following the last trading day of the 20 consecutive trading day period used to determine the acquisition termination market value.

The notice of acquisition termination redemption will specify, among other things:

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If any portion of the acquisition termination make-whole amount is to be satisfied through the delivery of shares of our common stock, no fractional shares of our common stock will be delivered to the holders of the Mandatory Convertible Preferred Stock. We will instead, to the extent permitted under Missouri law, pay a cash amount (computed to the nearest cent) to each holder that would otherwise be entitled to a fraction of share of our common stock based on the average VWAP per share of our common stock over the five consecutive trading day period commencing on, and including, the seventh scheduled trading day immediately preceding the scheduled acquisition termination redemption date. If the acquisition termination redemption date occurs on or prior to the last trading day of such five consecutive trading day period, payment of the cash payable in lieu of delivery of fractional shares of our common stock shall be deferred until the trading day immediately following the last business day of such five consecutive trading day period. If more than one share of Mandatory Convertible Preferred Stock is to be redeemed from a holder, the number of our shares of common stock issuable in connection with the payment of the reference amount shall be computed on the basis of the aggregate number of shares of Mandatory Convertible Preferred Stock so redeemed.

All cash payments to which a holder of the Mandatory Convertible Preferred Stock are entitled in connection with an acquisition termination redemption will be rounded to the nearest cent.

While we expect to use the net proceeds from this offering in connection with the Merger, there is no guarantee that the Merger will be consummated and if it is not consummated, we may use the proceeds of the offering for other purposes. We may, in our sole discretion, determine to redeem the Mandatory Convertible Preferred Stock as further described hereunder. The proceeds of this offering will not be deposited into an escrow account pending any acquisition termination redemption of the Mandatory Convertible Preferred Stock. Our ability to pay the acquisition termination make-whole amount to holders of the Mandatory Convertible Preferred Stock in connection with an acquisition termination redemption may be limited by our then-existing financial resources, and sufficient funds may not be available when necessary to make any required purchases of the Mandatory Convertible Preferred Stock following our election to redeem the Mandatory Convertible Preferred Stock.

To the extent a shelf registration statement is required in our reasonable judgment in connection with the issuance of, or for resales of, our shares of common stock issued as payment of any portion of the acquisition termination make-whole amount, we will, to the extent such a shelf registration statement is not currently filed and effective, use our reasonable best efforts to file and maintain the effectiveness of such a shelf registration statement until the earlier of such time as all such shares of our common stock have been resold thereunder and such time as all such shares would be freely tradable pursuant to Rule 144 under the Securities Act without registration by holders thereof that are not “affiliates” of ours (or were not our “affiliates” during the immediately preceding three months) for purposes of the Securities Act. To the extent applicable, we will also use our reasonable best efforts to have such shares of our common stock qualified or registered under applicable U.S. state securities laws, if required, and approved for listing on the NYSE (or if our shares of common stock are not listed on the NYSE, on the principal other U.S. national securities exchange on which shares of our common stock are then listed).

Other than pursuant to the acquisition termination redemption provisions described above, the Mandatory Convertible Preferred Stock will not be redeemable.

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Conversion Rights

Mandatory Conversion

Each outstanding share of Mandatory Convertible Preferred Stock will automatically convert on the third business day immediately following the last trading day of the final averaging period (the “mandatory conversion date”) into a number of shares of our common stock equal to the conversion rate described below, unless such share of the Mandatory Convertible Preferred Stock has been previously redeemed in the manner described in “— Acquisition Termination Redemption” or converted in the manner described in “— Early Conversion at the Option of the Holder” or “— Early Conversion at the Option of the Holder upon a Fundamental Change.”

The conversion rate, which is the number of shares of common stock issuable upon conversion of each share of Mandatory Convertible Preferred Stock on the mandatory conversion date (excluding shares of common stock, if any, issued in respect of accumulated and unpaid dividends), will be as follows:

We refer to the minimum conversion rate and the maximum conversion rate collectively as the “fixed conversion rates.”

If prior to the mandatory conversion date we have not declared all or any portion of the accumulated dividends on the Mandatory Convertible Preferred Stock, the conversion rate will be adjusted so that holders receive an additional number of shares of our common stock equal to the amount of such accumulated dividends that have not been declared and paid (the “additional conversion amount”), divided by the greater of (i) the floor price and (ii) 97% of the dividend payment average price with respect to the dividend payment date falling on September 15, 2019. To the extent that the additional conversion amount exceeds the product of such number of additional shares and 97% of the dividend payment average price with respect to the dividend payment date falling on September 15, 2019, we will, to the extent permitted under Missouri law, declare and pay such excess amount in cash to the holders of the Mandatory Convertible Preferred Stock.

The “applicable market value” of our common stock is the average VWAP per share of our common stock for the final averaging period. The “final averaging period” is the 20 consecutive trading day period commencing on, and including, the 22nd scheduled trading day prior to September 15, 2019.

Each of the fixed conversion rates, the initial price, the threshold appreciation price, the floor price, the fundamental change conversion rate and the applicable market value are subject to adjustment as described under “— Conversion Rights — Conversion Rate Adjustments” below.

Based on the foregoing, if the market price of our common stock on the mandatory conversion date is the same as the applicable market value, the aggregate market value of the shares of our common stock delivered upon mandatory conversion (other than any shares of our common stock received in connection with any dividend payment) will be:

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Early Conversion at the Option of the Holder

Other than during a fundamental change conversion period (as defined below in “— Early Conversion at the Option of the Holder upon a Fundamental Change”), and unless we have redeemed the Mandatory Convertible Preferred Stock, holders of the Mandatory Convertible Preferred Stock will have the right to convert all or any portion of their Mandatory Convertible Preferred Stock (but in no event less than one share of Mandatory Convertible Preferred Stock) at any time prior to the mandatory conversion date into shares of our common stock at the minimum conversion rate.

If, as of the effective date of any early conversion (the “early conversion date”), we have not declared all or any portion of the accumulated and unpaid dividends for all full dividend periods (including, for the avoidance of doubt, the dividend period ending on December 15, 2016) ending on the dividend payment date prior to such early conversion date, the conversion rate for such early conversion will be adjusted so that holders converting their shares of Mandatory Convertible Preferred Stock at such time receive an additional number of shares of our common stock equal to such amount of accumulated and unpaid dividends that have not been declared for such prior dividend periods, divided by the greater of (i) the floor price (as defined above under “— Method of Payment of Dividends”) and (ii) the average VWAP per share of our common stock over the 20 consecutive trading day period commencing on, and including, the 22nd scheduled trading day prior to the early conversion date (the “early conversion average price”). If, in respect of any early conversion date, the third business day immediately following such early conversion date occurs on or prior to the last trading day of such 20 consecutive trading day period, delivery of the shares of our common stock owed in respect of such early conversion shall be deferred until the business day immediately following the last trading day of such 20 consecutive trading day period. To the extent that the cash amount of the accumulated and unpaid dividends for prior dividend periods ending on a dividend payment date prior to the relevant early conversion date exceeds the value of the product of the number of additional shares added to the conversion rate and the early conversion average price, we will pay such excess amount in cash to the extent permitted under Missouri law.

Except as described above, upon any optional conversion of any Mandatory Convertible Preferred Stock, we will make no payment or allowance for unpaid dividends on such Mandatory Convertible Preferred Stock, unless such early conversion date occurs after the regular record date for a declared dividend and on or prior to the immediately succeeding dividend payment date, in which case such dividend will be paid on such dividend payment date to the holder of record of the converted shares of Mandatory Convertible Preferred Stock as of such regular record date, as described under “— Dividends” above.

Early Conversion at the Option of the Holder upon a Fundamental Change

If a “fundamental change” (as defined below) occurs on or prior to the mandatory conversion date, holders of the Mandatory Convertible Preferred Stock will have the right to:

(1) convert all or any portion of their Mandatory Convertible Preferred Stock (but in no event less than one share of Mandatory Convertible Preferred Stock):

(i) into shares of our common stock at the conversion rate determined using the table below (the “fundamental change conversion rate”); or

(ii) into units of exchange property based on the fundamental change conversion rate if the fundamental change also constitutes a reorganization event described under “— Recapitalizations, Reclassifications and Changes of Our Common Stock”;

(2) with respect to such converted shares, receive a fundamental change dividend make-whole amount (as defined below) payable in cash or shares of our common stock (or, if applicable, units of exchange property); and

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(3) with respect to such converted shares, receive the accumulated dividend amount (as defined below) payable in cash or shares of our common stock (or, if applicable, units of exchange property),

subject, in the case of clauses (2) and (3) above, to certain limitations with respect to the number of shares of our common stock that we will be required to deliver, all as described below in “— Fundamental Change Dividend Make-whole Amount and Accumulated Dividend Amount.”

Notwithstanding clauses (2) and (3) above, if the effective date of a fundamental change or the relevant fundamental change conversion date falls during a dividend period for which we have declared a dividend on the Mandatory Convertible Preferred Stock, we will pay such dividend on the relevant dividend payment date to the holders of record on the immediately preceding regular record date, as described in “— Dividends.” In such case the accumulated dividend amount will not include the amount of such dividend, and the fundamental change dividend make-whole amount will not include the present value of such dividend.

To exercise this right, holders must submit their Mandatory Convertible Preferred Stock for conversion at any time during the period (the “fundamental change conversion period”) from, and including, the effective date of such fundamental change (as defined below) (the “effective date”) to, but excluding, the earlier of (x) the mandatory conversion date and (y) the date selected by us that is not less than 30 and not more than 60 calendar days after the effective date (the “fundamental change conversion date”), at the fundamental change conversion rate. Holders of Mandatory Convertible Preferred Stock who do not submit their shares for conversion during the fundamental change conversion period will not be entitled to convert their Mandatory Convertible Preferred Stock at the fundamental change conversion rate or to receive the fundamental change dividend make-whole amount or, in connection with the fundamental change, the accumulated dividend amount.

We will notify holders, to the extent practicable, at least 20 calendar days prior to the anticipated effective date of such fundamental change, but in any event not later than two business days following our becoming aware of the occurrence of a fundamental change (the “fundamental change company notice”). Such fundamental change company notice will state, among other things, whether we have elected to satisfy all or any portion of accumulated and unpaid dividends through the delivery of shares of our common stock or units of exchange property, as the case may be, and, if so, the portion thereof (as a percentage) that will be satisfied through the delivery of shares of our common stock or units of exchange property.

The table below sets forth the fundamental change conversion rate per share of Mandatory Convertible Preferred Stock based on the effective date of the fundamental change and the stock price paid (or deemed paid) per share of our common stock in the fundamental change (as described below).

The exact stock price and effective date may not be set forth in the table, in which case:

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The “stock price” in the fundamental change will equal:

The stock prices set forth in the first row of the table (i.e., the column headers) will be adjusted as of any date on which the fixed conversion rates of the Mandatory Convertible Preferred Stock are adjusted. The adjusted stock prices will equal the stock prices applicable immediately prior to such adjustment, multiplied by a fraction, the numerator of which is the minimum conversion rate immediately prior to the adjustment giving rise to the stock price adjustment and the denominator of which is the minimum conversion rate as so adjusted. Each of the conversion rates in the table will be subject to adjustment at the same time and in the same manner as each fixed conversion rate as set forth under “— Conversion Rights — Conversion Rate Adjustments.”

A “fundamental change” will be deemed to have occurred if any of the following occurs:

(1) a “person” or “group” within the meaning of Section 13(d) of the Exchange Act, other than us, our subsidiaries and our or their employee benefit plans, has become the direct or indirect “beneficial owner,” as defined in Rule 13d-3 under the Exchange Act, of our common stock representing more than 50% of the voting power of our common equity;

(2) the consummation of (A) any recapitalization, reclassification or change of our common stock (other than a change only in par value, from par value to no par value or from no par value to par value, or changes resulting from a subdivision or combination of our common stock) as a result of which our common stock would be converted into, or exchanged for, or represent solely the right to receive, stock, other securities, other property or assets, (B) any share exchange, consolidation or merger of us pursuant to which our common stock will be converted into, or exchanged for, or represent solely the right to receive, stock, other securities, other property or assets or (C) any sale, lease or other transfer in one transaction or a series of transactions of all or substantially all of the consolidated assets of us and our subsidiaries, taken as a whole, to any person other than one of our wholly-owned subsidiaries;

(3) our stockholders approve any plan or proposal for the liquidation or dissolution of us; or

(4) our common stock (or, following a reorganization event (as defined below), any common stock, depositary receipts or other securities representing common equity interests into which the Mandatory Convertible Preferred Stock becomes convertible in connection with such reorganization event) ceases to be listed on any of the NYSE, The NASDAQ Global Select Market or The NASDAQ Global Market (or any of their respective successors).

A transaction or transactions described in clause (1) or (2) above will not constitute a fundamental change, however, if at least 90% of the consideration received or to be received by our common stockholders (excluding cash payments for fractional shares or pursuant to dissenters’ appraisal rights) in connection with such transaction or transactions consists of shares of common stock that are listed on any of the NYSE, The NASDAQ Global Select Market or The NASDAQ Global Market (or any of their respective successors), or will be so listed when issued or exchanged in connection with such transaction or transactions, and as a result of such transaction or transactions the Mandatory Convertible Preferred Stock becomes convertible into such consideration, excluding cash payments for fractional shares or pursuant to dissenters’ appraisal rights.

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Fundamental Change Dividend Make-whole Amount and Accumulated Dividend Amount

For any shares of Mandatory Convertible Preferred Stock that are converted during the fundamental change conversion period, in addition to the common stock issued upon conversion at the fundamental change conversion rate, we will at our option:

(1) pay holders in cash, to the extent permitted under Missouri law, the present value, computed using a discount rate of     % per annum, of all dividend payments on such holders’ shares of Mandatory Convertible Preferred Stock for all the remaining dividend periods (excluding any accumulated and unpaid dividends for all dividend periods ending on or prior to the dividend payment date preceding the effective date of the fundamental change, as well as dividends accumulated from the dividend payment date immediately preceding the effective date of the fundamental change to the effective date of the fundamental change) from such effective date to but excluding the mandatory conversion date (the “fundamental change dividend make-whole amount”);

(2) increase the number of shares of common stock to be issued on conversion by a number equal to (x) the fundamental change dividend make-whole amount divided by (y) the greater of the floor price and 97% of the stock price; or

(3) pay the fundamental change dividend make-whole amount in a combination of cash and shares of our common stock in accordance with the provisions of clauses (1) and (2) above.

In addition, for any shares of Mandatory Convertible Preferred Stock that are converted during the fundamental change conversion period, to the extent that, as of the effective date of the fundamental change, we have not declared any or all of the accumulated dividends on the Mandatory Convertible Preferred Stock as of such effective date (including accumulated and unpaid dividends for all dividend periods ending on or prior to the dividend payment date preceding the effective date of the fundamental change, as well as dividends accumulated from the dividend payment date immediately preceding the effective date of the fundamental change to the effective date of the fundamental change, the “accumulated dividend amount”), holders who convert their Mandatory Convertible Preferred Stock within the fundamental change conversion period will be entitled to receive such accumulated dividend amount upon conversion. The accumulated dividend amount will be payable at our election in either:

We will pay the fundamental change dividend make-whole amount and the accumulated dividend amount in cash, except to the extent we elect on or prior to the second business day following the effective date of a fundamental change to make all or any portion of such payments in shares of our common stock. In addition, if we elect to deliver shares of our common stock in respect of all or, in either case, any portion of the fundamental change dividend make-whole amount or accumulated dividend amount, to the extent that the fundamental change dividend make-whole amount or the accumulated dividend amount or any portion thereof that would be payable in shares of our common stock (without giving effect to the floor price) exceeds the product of the number of additional shares we deliver in respect thereof and 97% of the stock price, we will, to the extent permitted under Missouri law, declare and pay such excess amount in cash. In addition, if we are prohibited from paying or delivering, as the case may be, the fundamental change dividend make-whole amount or the accumulated dividend amount (in each case, whether in cash or in shares of our common stock), in whole or in part, due to limitations of applicable Missouri law, the fundamental change conversion rate will instead be increased by a number of shares of our common stock equal to the cash amount of the aggregate unpaid and undelivered fundamental change dividend make-whole amount and accumulated dividend amount, divided by the greater of (i) the floor price and (ii) 97% of the stock price. To the extent that the cash amount of the aggregate unpaid and undelivered fundamental change dividend make-whole amount and accumulated dividend amount exceeds the product of such number of additional shares and 97% of the stock price, we will not have any obligation to pay the shortfall in cash.

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Not later than the second business day following the effective date of a fundamental change (or, if we provide notice to holders of the fundamental change after the effective date of a fundamental change as described above, on the date we give holders notice of the effective date of a fundamental change), we will notify holders of:

Our obligation to adjust the conversion rate in connection with a fundamental change and pay the fundamental change dividend make-whole amount (whether in cash or shares of our common stock or any combination thereof) could be considered a penalty, in which case the enforceability thereof would be subject to general principles of reasonableness of economic remedies.

Conversion Procedures

Any outstanding shares of Mandatory Convertible Preferred Stock will automatically convert into shares of our common stock on the mandatory conversion date. The person or persons entitled to receive the shares of our common stock issuable upon conversion of the Mandatory Convertible Preferred Stock will be treated as the record holder(s) of such shares immediately prior to 5:00 p.m., New York City time, on the mandatory conversion date. Except as provided in “— Conversion Rate Adjustments,” prior to 5:00 p.m., New York City time, on the mandatory conversion date, the shares of our common stock issuable upon conversion of the Mandatory Convertible Preferred Stock will not be outstanding for any purpose and holders of the Mandatory Convertible Preferred Stock will have no rights with respect to such shares of common stock, including, without limitation, voting rights, rights to participate in tender offers and rights to receive any dividends or other distributions on our common stock, in each case by virtue of holding the Mandatory Convertible Preferred Stock.

If a holder elects to convert its shares of Mandatory Convertible Preferred Stock prior to the mandatory conversion date, in the manner described in “— Early Conversion at the Option of the Holder,” or “— Early Conversion at the Option of the Holder upon a Fundamental Change,” such holder must observe the following conversion procedures:

The conversion date will be the date on which the converting holder has satisfied the foregoing requirements. A holder who converts its shares of Mandatory Convertible Preferred Stock will not be required to pay any taxes or duties relating to the issuance or delivery of shares of our common stock if such holder exercises its conversion rights, but such holder will be required to pay any tax or duty that may be payable relating to any transfer involved in the issuance or delivery of the shares of common stock in a name other than its own.

Shares of common stock will be issued and delivered only after all applicable taxes and duties, if any, payable by the converting holder have been paid in full and will be issued on the later of the third business day immediately succeeding the conversion date and the business day after such holder has paid in full all applicable taxes and duties, if any.

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The person or persons entitled to receive the common stock issuable upon conversion of the Mandatory Convertible Preferred Stock prior to the mandatory conversion date will be treated as the record holder(s) of such shares immediately prior to 5:00 p.m., New York City time, on the applicable conversion date. Prior to 5:00 p.m., New York City time, on the applicable conversion date, the common stock issuable upon conversion of the Mandatory Convertible Preferred Stock will not be outstanding for any purpose and a holder of the Mandatory Convertible Preferred Stock will have no rights with respect to such common stock, including voting rights, rights to participate in tender offers and rights to receive any dividends or other distributions on the common stock, by virtue of holding the Mandatory Convertible Preferred Stock. No fractional shares of our common stock will be issued to holders of shares of the Mandatory Convertible Preferred Stock upon conversion. In lieu of any fractional shares of common stock otherwise issuable upon conversion (including in connection with a dividend payment), that holder will be entitled to receive an amount in cash (computed to the nearest cent) based on the VWAP per share of our common stock on the trading day immediately preceding the applicable conversion date. If more than one share of the Mandatory Convertible Preferred Stock is surrendered for conversion at one time by or for the same holder, the number of full shares of our common stock issuable upon conversion thereof shall be computed on the basis of the aggregate number of shares of the Mandatory Convertible Preferred Stock so surrendered.

Conversion Rate Adjustments

Each fixed conversion rate will be adjusted from time to time as follows:

(i) If we issue our common stock as a dividend or distribution to all or substantially all holders of our common stock, or if we effect a subdivision or combination (including, without limitation, a stock split or a reverse stock split) of our common stock, each fixed conversion rate will be adjusted based on the following formula:

Where,

Any adjustment made under this clause (i) will become effective immediately after 5:00 p.m., New York City time, on the record date for such dividend or distribution, or immediately after 9:00 a.m., New York City time, on the effective date for such subdivision or combination, as the case may be. If any dividend or distribution of the type described in this clause (i) is declared but not so paid or made, each fixed conversion rate will be immediately readjusted, effective as of the earlier of (a) the date our board of directors or a duly authorized committee thereof determines not to pay or make such dividend or distribution and (b) the date the dividend or distribution was to be paid, to the fixed conversion rate that would then be in effect if such dividend or distribution had not been declared.

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(ii) If we issue to all or substantially all holders of our common stock any rights, options or warrants entitling them for a period expiring 60 calendar days or less from the date of issuance of such rights, options or warrants to subscribe for or purchase shares of our common stock at less than the average VWAP per share of our common stock for the 10 consecutive trading day period ending on, and including, the trading day immediately preceding the date of announcement for such issuance, each fixed conversion rate will be increased based on the following formula:

where,

Any increase in the fixed conversion rates made pursuant to this clause (ii) will become effective immediately after 5:00 p.m., New York City time, on the record date for such issuance. To the extent such rights, options or warrants are not exercised prior to their expiration or termination, each fixed conversion rate will be decreased, effective as of the date of such expiration or termination, to the fixed conversion rate that would then be in effect had the increase with respect to the issuance of such rights, options or warrants been made on the basis of delivery of only the number of shares of common stock actually delivered. If such rights, options or warrants are not so issued, each fixed conversion rate will be decreased, effective as of the earlier of (a) the date our board of directors or a duly authorized committee thereof determines not to issue such rights, options or warrants and (b) the date such rights, options or warrants were to have been issued, to the fixed conversion rate that would then be in effect if such issuance had not been announced.

For purposes of this clause (ii), in determining whether any rights, options or warrants entitle the holders thereof to subscribe for or purchase shares of our common stock at less than average VWAP per share of our common stock for the 10 consecutive trading day period ending on, and including, the trading day immediately preceding the date of announcement for such issuance, and in determining the aggregate price payable to exercise such rights, options or warrants, there will be taken into account any consideration we receive for such rights, options or warrants and any amount payable on exercise thereof, with the value of such consideration, if other than cash, to be determined by our board of directors or a duly authorized committee thereof, which determination shall be final.

(iii) If we pay a dividend or other distribution to all or substantially all holders of our common stock of shares of our capital stock (other than our common stock), evidences of our indebtedness, our assets or rights to acquire our capital stock, our indebtedness or our assets, excluding:

(a) any dividend, distribution or issuance as to which an adjustment was effected pursuant to clause (i) or (ii) above;

(b) dividends or distributions paid exclusively in cash as to which clause (iv) below applies;

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(c) “spin-offs” as to which the provisions set forth below in this clause (iii) apply; and

(d) any dividends or distributions in connection with a reorganization event that is included in exchange property as described below under “— Recapitalizations, Reclassifications and Changes of Our Common Stock”;

then each fixed conversion rate will be increased based on the following formula:

where,

If our board of directors or a duly authorized committee thereof determines the “FMV” (as defined above) of any dividend or other distribution for purposes of this clause (iii) by referring to the actual or when-issued trading market for any securities, it will in doing so consider the prices in such market over the average VWAP per share of our common stock for the 10 consecutive trading day period ending on, and including, the trading day immediately preceding the ex-dividend date for such dividend or distribution.

Notwithstanding the foregoing, if “FMV” (as defined above) is equal to or greater than “SP₀” (as defined above), in lieu of the foregoing increase, each holder of shares of the Mandatory Convertible Preferred Stock will receive, in respect of each share thereof, at the same time and upon the same terms as holders of our common stock and solely as a result of holding shares of Mandatory Convertible Preferred Stock, the amount and kind of shares of our capital stock (other than our common stock), evidences of our indebtedness, our assets or rights to acquire our capital stock, our indebtedness or our assets that such holder would have received if such holder owned a number of shares of our common stock equal to the maximum conversion rate in effect immediately prior to 5:00 p.m., New York City time, on the record date for such dividend or other distribution.

Any increase made under the portion of this clause (iii) above will become effective immediately after 5:00 p.m., New York City time, on the record date for such dividend or other distribution. If such dividend or other distribution is not so paid or made, each fixed conversion rate will be decreased, effective as of the earlier of (a) the date our board of directors or a duly authorized committee thereof determines not to pay the dividend or other distribution and (b) the date such dividend or distribution was to have been paid, to the fixed conversion rate that would then be in effect if the dividend or other distribution had not been declared.

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If the transaction that gives rise to an adjustment pursuant to this clause (iii) is one pursuant to which the payment of a dividend or other distribution on our common stock consists of shares of capital stock of, or similar equity interests in, a subsidiary or other business unit of ours (i.e., a spin-off) that are, or, when issued, will be, traded on a U.S. national securities exchange or a reasonably comparable non-U.S. equivalent (as determined in good faith by our board of directors or a duly authorized committee thereof), then each fixed conversion rate will be increased based on the following formula:

where,

The adjustment to each fixed conversion rate under the immediately preceding paragraph will occur at 5:00 p.m., New York City time, on the 10th consecutive trading day immediately following, and including, the ex-dividend date for such dividend or distribution, but will be given effect as of 9:00 a.m., New York City time, on the date immediately following the record date for such dividend or distribution. Because we will make the adjustments to the fixed conversion rates at the end of the 10 consecutive trading day period with retroactive effect, we will delay the settlement of any conversion of shares of the Mandatory Convertible Preferred Stock if the conversion date occurs after the record date for such dividend or other distribution and prior to the end of such 10 consecutive trading day period. In such event, we will deliver the shares of common stock issuable in respect of such conversion (based on the adjusted fixed conversion rates as described above) on the first business day immediately following the last trading day of such 10 consecutive trading day period.

(iv) If we pay a distribution consisting exclusively of cash to all or substantially all holders of our common stock, excluding (A) any regular quarterly cash dividends or distributions of up to $0.2625 per share of our common stock (the “initial dividend threshold”), (B) any distribution in connection with our voluntary or involuntary liquidation, dissolution or winding up, (C) any distribution in connection with a reorganization event that is included in exchange property as described below under “— Recapitalizations, Reclassifications and Changes of Our Common Stock” and (D) any consideration paid as part of a tender or exchange offer covered by clause (v) below, each fixed conversion rate will be increased based on the following formula:

where,