Founded in 1930 and headquartered in Glen Allen, VA, Markel Corporation markets and underwrites specialty insurance products in the United States, the United Kingdom, Canada, and internationally.

Starting from first-quarter 2018, Markel has revised its reportable segments keeping in mind its sustained growth as well as diversification. Effective Jan 1, 2018, the company reported through two segments, namely Insurance and Reinsurance.  

The Insurance segment (89.8% of 2023 gross premium) offers general and professional liability, property, personal lines, marine and energy, specialty programs, and workers' compensation insurance products. Business in this segment is primarily written through Markel Assurance, Markel Specialty and Markel International divisions. As a result of the acquisition of State National Companies, Inc. (State National), effective November 2017, the company created the State National division. The State National division's collateral protection underwriting business is included in the Insurance segment.

The Reinsurance segment (10.2%) includes property and casualty treaty reinsurance products offered to other insurance and reinsurance companies globally through the broker market. Treaty reinsurance offerings include both quota share and excess of loss reinsurance and are typically written on a participation basis, which means each reinsurer has a proportional share in the business ceded under the reinsurance treaty written.

Markel Ventures: Through wholly owned subsidiary Markel Ventures, Inc. (Markel Ventures), the company own interests in various businesses that operate outside of the specialty insurance marketplace. These businesses are viewed by management as separate and distinct from insurance operations. Local management teams oversee the day-to-day operations of these companies, while strategic decisions, including investment and capital allocation decisions, are made by senior management.