SCHEDULE 13D/A 0000902664-24-005842 0002040467 XXXXXXXX LIVE 3 Common Stock, par value $0.01 per share 05/20/2025 false 0000842633 896215209 TRIMAS CORP

38505 WOODWARD AVENUE SUITE 200 BLOOMFIELD HILLS MI 48304

Trend International Holding AG 41 44 268 69 38 Wiesenstrasse 9 Zurich V8 8008 Ele Klein & Sean W. Brownridge 212-756-2000 Schulte Roth & Zabel LLP 919 Third Avenue New York NY 10022 0002040467 N Trend International Holding AG WC N V8 0.00 4170667.00 0.00 4170667.00 4170667.00 N 10.3 CO 0001321614 N Shawn Sedaghat AF N X1 4140.00 6054425.00 4140.00 6054425.00 6054425.00 N 14.9 IN The 6,058,565 shares of Common Stock include a total of (i) 4,140 shares of Common Stock underlying RSUs (as defined in Item 3) directly held by Mr. Sedaghat and (ii) 6,054,425 shares of Common Stock held by Trend and Swan. Common Stock, par value $0.01 per share TRIMAS CORP 38505 WOODWARD AVENUE SUITE 200 BLOOMFIELD HILLS MI 48304 This Amendment No. 3 ("Amendment No. 3") amends the statement on Schedule 13D filed by the Reporting Persons on October 15, 2024, with the Securities and Exchange Commission (the "SEC") (as amended, the "Schedule 13D") with respect to the shares of common stock, par value $0.01 per share ("Common Stock") of TriMas Corporation, a Delaware corporation (the "Issuer"). Capitalized terms used herein and not otherwise defined in this Amendment No. 3 have the meanings set forth in the Schedule 13D. This Amendment No. 3 amends and restates Items 3 and 5 (a)-(c) and supplements Item 6 as set forth below. The aggregate cost of the shares of Common Stock beneficially owned by the Reporting Persons is approximately $152,249,300 USD, excluding brokerage commissions. The shares were purchased with the working capital of Trend and Swan. Positions in the shares of Common Stock may be held in margin accounts and may be pledged as collateral security for the repayment of debit balances in such accounts. Because other securities may be held in such margin accounts, it may not be possible to determine the amounts, if any, of margin used to purchase the shares of Common Stock. The 4,140 shares of Common Stock underlying restricted stock units ("RSUs") reported herein are directly held by Mr. Sedaghat and were issued in consideration for his service on the Board. See rows (11) and (13) of the cover pages to the Schedule 13D for the aggregate number of shares of Common Stock and percentage of shares of Common Stock beneficially owned by the Reporting Persons. The aggregate percentage of shares of Common Stock reported beneficially owned by the Reporting Persons is based upon 40,651,688 shares of Common Stock outstanding as of April 22, 2025, as disclosed in the Quarterly Report on Form 10-Q for the quarterly period ended March 31, 2025, filed by the Issuer with the SEC on April 29, 2025, and assumes the shares of Common Stock underlying the RSUs reported herein are outstanding. See rows (7) through (10) of the cover pages to the Schedule 13D for the shares of Common Stock as to which the Reporting Persons have the sole or shared power to vote or direct the vote and sole or shared power to dispose or to direct the disposition. The transactions in the shares of Common Stock effected by the Reporting Persons during the past sixty (60) days, which were all in the open market, are set forth on Schedule 1 attached hereto and is incorporated herein by reference. On March 14, 2025, Mr. Sedaghat received a grant of 4,140 RSUs in consideration for his service on the Board. These RSUs will vest on March 14, 2026. Trend International Holding AG /s/ Shawn Sedaghat 05/22/2025 Shawn Sedaghat /s/ Shawn Sedaghat 05/22/2025