<Page> Exhibit 4.1 PAGE 1 DELAWARE THE FIRST STATE I, HARRIET SMITH WINDSOR, SECRETARY OF STATE OF THE STATE OF DELAWARE, DO HEREBY CERTIFY THE ATTACHED IS A TRUE AND CORRECT COPY OF THE CERTIFICATE OF STATUTORY TRUST REGISTRATION OF "AMG CAPITAL TRUST I", FILED IN THIS OFFICE ON THE TWENTY-EIGHTH DAY OF MARCH, A.D. 2006, AT 5:30 O'CLOCK P.M. /s/ Harriet Smith Windsor ---------------------------------------- [SEAL] Harriet Smith Windsor, Secretary of State AUTHENTICATION: 4630672 DATE: 03-29-06 4133367 8100 060299258 <Page> STATE OF DELAWARE SECRETARY OF STATE DIVISION OF CORPORATIONS DELIVERED 05:39 PM 03/28/2006 FILED 05:30 PM 03/28/2006 SRV 060294801 - 4133367 FILE CERTIFICATE OF TRUST OF AMG CAPITAL TRUST I THIS Certificate of Trust of AMG Capital Trust I (the "Trust") is being duly executed and filed by the undersigned to form a statutory trust under the Delaware Statutory Trust Act (12 DEL. C. Section 3801 ET SEQ.) (the "Act"). 1. NAME. The name of the statutory trust formed hereby is AMG Capital Trust I. 2. DELAWARE TRUSTEE. The name and business address of the trustee of the Trust in the State of Delaware are Christiana Bank & Trust Company, 1314 King Street, Wilmington, DE 19801. 3. EFFECTIVE DATE. This Certificate of Trust shall be effective upon filing. IN WITNESS WHEREOF, the undersigned has executed this Certificate of Trust in accordance with Section 381l(a) of the Act. CHRISTIANA BANK & TRUST COMPANY, not in its individual capacity but solely as Delaware Trustee By: /s/ James M. Young ------------------------------------ Name: JAMES M. YOUNG Title: ASSISTANT VICE PRESIDENT <Page> PAGE 1 DELAWARE THE FIRST STATE I, HARRIET SMITH WINDSOR, SECRETARY OF STATE OF THE STATE OF DELAWARE, DO HEREBY CERTIFY "AMG CAPITAL TRUST I" IS DULY FORMED UNDER THE LAWS OF THE STATE OF DELAWARE AND IS IN GOOD STANDING AND HAS A LEGAL EXISTENCE SO FAR AS THE RECORDS OF THIS OFFICE SHOW, AS OF THE TWENTY-NINTH DAY OF MARCH, A.D. 2006. /s/ Harriet Smith Windsor ---------------------------------------- [SEAL] Harriet Smith Windsor, Secretary of State AUTHENTICATION: 4630675 DATE: 03-29-06 4133367 8300 060299262