OGE ENERGY CORP

You may vote by mail, by telephone, by Internet, or online during the meeting. Please refer to the summary instructions below and those included on your Notice of Internet Availability of Proxy Materials or your proxy card or, for shares held in street name, the voting instruction card you received from your broker or nominee. To vote by mail, simply complete and sign the proxy card and mail it in the prepaid and pre-addressed envelope. If you received a Notice of Internet Availability of Proxy Materials, you may request a proxy card by following the instructions in your Notice. If you mark your voting instructions on the proxy card, your shares will be voted as you instruct. If you return a signed card but do not provide voting instructions, your shares will be voted for each proposal in accordance with the recommendations of the Board for such proposals.

Shareholders of record also may vote by the Internet or by using the toll-free number listed on your Notice of Internet Availability of Proxy Materials or the proxy card. The telephone voting and Internet voting procedures are designed to verify shareholders through use of an identification number that will be provided to you. During the meeting, you may vote online by following the instructions at www.virtualshareholdermeeting.com/OGE2024. Have your Notice, proxy card or voting instruction form available when you access the virtual meeting web page.

1 OGE Energy Corp.2024 Proxy Statement

Only shareholders of record or their legal proxy holders as of the record date may attend the annual meeting. To attend and participate in the virtual meeting, you will need the 16-digit control number included on your Notice, proxy card or voting instruction form. No recording of the annual meeting will be permitted.

If your shares are held in a stock brokerage account or by a bank or other nominee, you are considered the beneficial owner of shares held in street name and your broker or nominee is considered, with respect to those shares, the shareholder of record.

Brokerage firms have authority under New York Stock Exchange ("NYSE") rules to vote customers' shares for which they have not received voting instructions on certain "routine" matters, but may not vote for non-routine matters unless they have received voting instruction. The only "routine" matter at this year's annual meeting is the ratification of the Company's principal independent accountants. Brokers will not be able to vote their customers' shares for the election of directors, for the advisory vote on executive compensation or for the shareholder proposal regarding simple majority voting unless their customers return voting instructions. Therefore, if your shares are held in street name by your bank or broker, it is important for you to return your voting instructions in order that your shares are voted for these matters.