UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

Pursuant to section 13 or 15(d) of

The Securities Exchange Act of 1934

Date of Report: June 27, 2012

(Date of earliest event reported)

Markel Corporation

(Exact name of registrant as specified in its charter)

4521 Highwoods Parkway

Glen Allen, Virginia 23060-6148

(804) 747-0136

(Address, including zip code, and telephone number, including area code, of registrant’s principal executive offices)

(Former name or former address, if changed since last report.)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions (see General Instruction A.2. below):

On June 27, 2012, Markel Corporation (the “Company”) executed an Underwriting Agreement and related pricing agreement (the “Underwriting Agreement”) with the underwriters named therein. Under the Underwriting Agreement, the Company is issuing $350,000,000 aggregate principal amount of its 4.90% Senior Notes due 2022 (the “Securities”) under the Indenture dated as of June 5, 2001 (the “Indenture”), between the Company and The Bank of New York Mellon (as successor to The Chase Manhattan Bank), as trustee (the “Trustee”), relating to debt securities, as amended by a Seventh Supplemental Indenture to the Indenture, to be dated as of July 2, 2012 (the “Seventh Supplemental Indenture”). The Underwriting Agreement, the form of the Seventh Supplemental Indenture and the Computation of Earnings to Fixed Charges Ratio are filed as exhibits hereto and are incorporated herein by reference. The form of the Securities is included as Exhibit A to the form of the Seventh Supplemental Indenture.

Certain exhibits are filed herewith by the Company, in connection with the Company’s offering of the Securities pursuant to its Prospectus Supplement, dated June 27, 2012, to the Prospectus, dated December 16, 2011, filed with the Securities and Exchange Commission as part of the Registration Statement on Form S-3 (Registration No. 333-178556).

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

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