Filing Details

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 SCHEDULE 13G Under the Securities Exchange Act of 1934 (Amendment No. )*TriMas Corp. (Name of Issuer) COMMON STOCK NO PAR VALUE (Title of Class of Securities) 896215209 (CUSIP Number) DECEMBER 31, 2016 (Date of Event Which Requires Filing of this Statement) Check the appropriate box to designate the rule pursuant to which this Schedule is filed: [ X ] Rule 13d-1(b) [ ] Rule 13d-1(c) [ ] Rule 13d-1(d) *The remainder of this cover page shall be filled out for a reporting person's initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter the disclosures provided in a prior cover page. The information required in the remainder of this cover page shall not be deemed to be "filed" for the purpose of Section 18 of the Securities Exchange Act of 1934 ("Act") or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

Item 1. (a) TriMas Corp. (b) 39400 Woodward Avenue Suite 130 Bloomfield Hills, MI 48304 United States Item 2. (a) Fiduciary Management, Inc. (b) 100 East Wisconsin Avenue Suite 2200 Milwaukee, WI 53202 United States (c) Wisconsin (d) Common Stock (e) 896215209 Item 3. (a) [ ] Broker or dealer registered under section 15 of the Act (15 U.S.C. 78o). (b) [ ] Bank as defined in section 3(a)(6) of the Act (15 U.S.C. 78c). (c) [ ] Insurance company as defined in section 3(a)(19) of the Act (15 U.S.C. 78c). (d) [ ] Investment company registered under section 8 of the Investment Company Act of 1940 (15 U.S.C 80a-8). (e) [ X ] An investment adviser in accordance with 240.13d-1(b)(1)(ii)(E); (f) [ ] An employee benefit plan or endowment fund in accordance with 240.13d-1(b)(1)(ii)(F); (g) [ ] A parent holding company or control person in accordance with 240.13d-1(b)(1)(ii)(G); (h) [ ] A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act; (i) [ ] A church plan that is excluded from the definition of an investment company under section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3); (j) [ ] Group, in accordance with 240.13d-1(b)(1)(ii)(J).Item 4. Ownership. (a) Amount beneficially owned: 2,513,010 (b) Percent of class: 5.52% (c) Number of shares as to which the person has: 2,513,010Item 5. Ownership of Five Percent or Less of a Class If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following [ ]. Instruction: Dissolution of a group requires a response to this item.Item 6. Ownership of More than Five Percent on Behalf of Another Person. Fiduciary Management, Inc. is an Investment Adviser registered under the Investment Advisers Act of 1940. Its Principal Business is to provide investment advisory services to institutions and individuals. The shares to which this statement relates are owned directly by various accounts managed by Fiduciary Management, Inc. Such accounts have the right to receive dividends from, and the proceeds from the sale of, the shares. Item 7. Identification and Classification of the Subsidiary Which Acquired the Security Being Reported on By the Parent Holding Company or Control Person. Item 8. Identification and Classification of Members of the Group Item 9. Notice of Dissolution of Group Item 10. Certification