Notice of 2021 Annual Meeting of Stockholders and Proxy Statement The Road Ahead — There are No Boundaries LETTER TO STOCKHOLDERS January 29, 2021 Dear Navistar Stockholder: On behalf of the board of directors (the ‘‘Board’’) of Navistar International Corporation (the ‘‘Company’’ or ‘‘Navistar’’), you are cordially invited to attend our 2021 Annual Meeting of Stockholders (the ‘‘Annual Meeting’’). The Annual Meeting will be held virtually on March 2, 2021, at 11:00 a.m., Central Time. In light of the ongoing coronavirus (‘‘COVID-19’’) pandemic, for the safety of our stockholders and in accordance with federal, state and local guidance limiting group gatherings, the Annual Meeting will be held in a virtual meeting format only, and there will not be a physical meeting location. You will be able to attend, vote and submit questions during the virtual Annual Meeting online by visiting www.virtualshareholdermeeting.com/NAV2021. The Annual Meeting will be held for the purpose of Navistar stockholders considering and voting on the following proposals: • To consider and vote on a proposal to adopt the Agreement and Plan of Merger, dated as of November 7, 2020, as it may be amended from time to time (the ‘‘Merger Agreement’’), by and among the Company, TRATON SE, a Societas Europaea (‘‘Parent’’ or ‘‘TRATON’’), and Dusk Inc., a Delaware corporation and wholly owned indirect subsidiary of Parent (‘‘Merger Sub’’); • To consider and vote on a proposal to approve, by non-binding, advisory vote, certain compensation arrangements for the Company’s named executive officers in connection with the Merger; • To elect as directors the nominees named in the accompanying proxy statement; • To consider and vote on a non-binding, advisory vote on executive compensation as disclosed in the accompanying proxy statement; • To ratify the appointment of the Company’s independent registered public accounting firm; and • To approve the adjournment or postponement of the Annual Meeting, if necessary, to continue to solicit votes for the Merger Proposal. On November 7, 2020, the Company, Parent and Merger Sub entered into the Merger Agreement. The Merger Agreement provides for, among other things, the acquisition by Parent of the Company through the merger of Merger Sub with and into the Company (the ‘‘Merger’’), with the Company continuing as the surviving corporation and a wholly owned indirect subsidiary of Parent. If the Merger is completed, you will be entitled to receive $44.50 in cash, without interest, for each share of the Company’s common stock owned by you, which represents a premium of approximately 84.88% to the closing price of the Company’s common stock as of January 30, 2020, the last trading day prior to the announcement by Parent of its unsolicited offer to acquire the Company for $35.00 per share, and a 58.14% premium to the volume-weighted average price of shares of the Company’s common stock for the 30 trading days ended January 30, 2020, a premium of approximately 24.16% to the closing price of the Company’s common stock as of September 9, 2020, the last trading day prior to the Company’s confirmation of a revised proposal from Parent to acquire the Company for $43.00 per share and a premium of approximately 2.6% to the closing price of the Company’s common stock as of November 6, 2020, the last trading day prior to the public announcement of the execution of the Merger Agreement. Concurrently with the execution of the Merger Agreement, certain stockholders of the Company affiliated with Carl C. Icahn (collectively, the ‘‘Icahn Stockholders’’), and certain stockholders of the Company affiliated with Mark H. Rachesky (collectively, the ‘‘MHR Stockholders’’) entered into voting and support agreements with Parent and Merger Sub (the ‘‘Voting Agreements’’), pursuant to which the Icahn Stockholders and the MHR Stockholders have agreed to, among other things, vote in favor of the adoption of the Merger Agreement and the transactions contemplated by the Merger Agreement. As of January 22, 2021, the Icahn Stockholders collectively own approximately 16.8% of the outstanding shares of the Company’s common stock, and the MHR Stockholders collectively own approximately 16.4% of the outstanding shares of the Company’s common stock. Additionally, as of January 22, 2021, Parent and its affiliates collectively own approximately 16.7% of the outstanding shares of the Company’s common stock which, pursuant to the Merger Agreement, Parent has committed to vote in favor of the adoption of the Merger Agreement and the transactions contemplated by the Merger Agreement. 2021 Proxy Statement i The Board has determined that the Merger and the other transactions contemplated by the Merger Agreement are fair to, and in the best interest of, the Company and the stockholders of the Company and approved and declared advisable the Merger Agreement, the Merger, the other transactions contemplated by the Merger Agreement and the Voting Agreements. The Board made its determination after consultation with its legal and financial advisors and consideration of a number of factors. Approval of the proposal to adopt the Merger Agreement requires the affirmative vote of a majority of the shares of our common stock outstanding and entitled to vote on such proposal. The affirmative vote of a majority of the shares present virtually or represented by proxy at the Annual Meeting and entitled to vote on the non-binding advisory vote on certain compensation arrangements for the Company’s named executive officers in connection with the Merger will constitute the stockholders’ non-binding advisory approval of the Merger Compensation Proposal. The approval of each of the director nominees named in the accompanying proxy statement requires the affirmative vote of a plurality of the shares present virtually or represented by proxy at the Annual Meeting and entitled to vote on each director nominee in such proposal. The affirmative vote of a majority of shares present virtually or represented by proxy at the Annual Meeting and entitled to vote on the non-binding, advisory vote on executive compensation as disclosed in the accompanying proxy statement will constitute the stockholders’ non-binding advisory approval of such proposal. The approval to ratify the appointment of the Company’s independent registered public accounting firm requires the affirmative vote of a majority of the shares present virtually or represented by proxy at the Annual Meeting and entitled to vote on such proposal. THE BOARD RECOMMENDS THAT YOU VOTE ‘‘FOR’’ EACH OF THE PROPOSALS SET FORTH IN THIS PROXY STATEMENT. Your vote is very important. Whether or not you plan to attend the Annual Meeting virtually, please submit your proxy by telephone, scanning your QR Code or via the Internet, or, if you request that the proxy materials be mailed to you, please complete, date, sign and return, as promptly as possible, the enclosed proxy card in the accompanying postage-paid reply envelope. If you virtually attend the Annual Meeting and vote your shares at the meeting electronically, your vote by ballot will revoke any proxy previously submitted. You may revoke your proxy before the Annual Meeting, by voting by telephone, scanning your QR Code or over the Internet (only your latest telephone, QR Code or Internet vote is counted) or by signing a new proxy and mailing it, in each case, in accordance with the instructions on the enclosed proxy card. In addition, you may revoke your proxy by attending the Annual Meeting virtually, requesting that your proxy be revoked and voting your shares electronically at the Annual Meeting; however, attending the Annual Meeting virtually will not revoke your telephone vote, QR Code vote or Internet vote or proxy, as the case may be, unless you specifically request it. If you fail to return your proxy card, submit your proxy by telephone, scanning your QR Code or via the Internet or vote your shares electronically at the Annual Meeting, your shares of our common stock will NOT be counted for purposes of determining whether a quorum is present at the Annual Meeting and will have the same effect as a vote ‘‘AGAINST’’ approval of the proposal to adopt the Merger Agreement. If you fail to return your proxy card, submit your proxy by telephone, scanning your QR Code or via the Internet or vote your shares electronically at the Annual Meeting, your shares of our common stock will not have an effect on the Merger Compensation Proposal, the Election of Directors Proposal, the Say-On-Pay Proposal and the Adjournment Proposal. If your shares of our common stock are held in ‘‘street name’’ by your bank, brokerage firm or other nominee, your bank, brokerage firm or other nominee will be unable to vote your shares of our common stock without instructions from you except for with respect to ‘‘routine’’ matters. You should instruct your bank, brokerage firm or other nominee to vote your shares of our common stock in accordance with the procedures provided by your bank, brokerage firm or other nominee. If your shares are held in ‘‘street name’’ by your bank, brokerage firm or other nominee and you fail to instruct your bank, brokerage firm or other nominee to vote your shares of common stock, your shares of our common stock will still be counted for purposes of determining whether a quorum is present at the Annual Meeting and will have the same effect as a vote ‘‘AGAINST’’ approval of the proposal to adopt the Merger Agreement. If your shares are held in ‘‘street name’’ by your bank, brokerage firm or other nominee and you fail to instruct your bank, brokerage firm or other nominee to vote your shares of common stock, your shares of our common stock will not have an effect on the Merger Compensation Proposal, the Election of Directors Proposal, the Say-On-Pay Proposal and the Adjournment Proposal.