Aspen Insurance business insurance

Overview

Aspen is a Bermuda-based specialty insurer and reinsurer that brokers know for excess casualty, environmental, professional and management liability capacity. In the NAIC's 2025 data it still sits under Apollo Global Management, which owned it from 2019; that group was ranked No. 68 among U.S. business insurers by 2025 commercial lines direct premiums written, with $1.18 billion, based on NAIC market share data. It does not rank in the national top 10 in any line. Other liability, at $864.2 million, is almost three-quarters of the total, followed by inland marine, medical professional liability and allied lines property.

The ownership has since changed. Sompo Holdings of Japan completed its purchase of Aspen on February 24, 2026, and Aspen is moving to the Sompo brand. Aspen's U.S. insurers are Aspen American Insurance Company, an admitted carrier domiciled in Texas, and Aspen Specialty Insurance Company, a surplus lines carrier domiciled in North Dakota, both run from Rocky Hill, Connecticut. The NAIC's Apollo group also listed three other Apollo-affiliated insurers that are not part of Aspen: Alea North America Insurance Company, National American Insurance Company of California and Sparta Insurance Company.

Aspen sells only through brokers, retail and wholesale, and some professional lines programs run under delegated authority. Outside the U.S. it writes through Aspen Insurance UK, Aspen Bermuda and Lloyd's Syndicate 4711, alongside a reinsurance business and Aspen Capital Partners, which manages third-party capital.

History

Aspen Insurance Holdings was registered in Bermuda in May 2002 and later listed on the New York Stock Exchange, building insurance and reinsurance operations in Bermuda, London and the U.S.

• February 15, 2019: Funds managed by Apollo Global Management completed their purchase of Aspen for $42.75 a share in cash, about $2.6 billion of equity value, taking it private. Mark Cloutier became executive chairman and group CEO.
• May 2025: Apollo began selling down its stake through an IPO priced at $30 a share; the shares began trading on the NYSE under AHL, and the offering raised $397.5 million for the selling shareholders.
• August 27, 2025: Sompo Holdings agreed to buy all of Aspen's Class A shares for $37.50 each in cash, about $3.5 billion, a 35.6% premium to the August 19 closing price.
• February 24, 2026: Sompo completed the acquisition through a subsidiary of Sompo International Holdings. Aspen's Class A shares stopped trading on the NYSE (its preference shares stayed listed), Aspen began moving to the Sompo brand, and Cloutier moved to an advisory role.
• September 10, 2026: AM Best upgraded Aspen's operating companies, including both U.S. carriers, to A+ (Superior), citing their integration with Sompo Japan.

Sompo said the deal would add Aspen's insurance and reinsurance portfolios and a larger U.K. presence to its global property and casualty platform. Sompo's own U.S. specialty business runs through the Endurance companies; see Sompo and when your insurer is sold or merges: what happens to your policy for what a change of owner means for policies already in force.

Business insurance products

Aspen's U.S. book, as described on Sompo's legacy Aspen pages in 2026:

• Excess casualty: excess umbrella, follow form and stand-alone liability on occurrence, claims-made or occurrence-reported triggers, with punitive damages cover available, on admitted, surplus lines or self-procured paper. See umbrella vs excess liability.
• U.S. primary casualty: general liability and products/completed operations, including liquor liability, with limits from $1 million/$2 million/$2 million up to $2 million/$4 million/$4 million, annual or project terms up to 60 months, and guaranteed cost, deductibles or SIRs. Minimum premium is generally $50,000.
• Railroad liability: freight and passenger railroads, railcar lessors, railroad contractors and suppliers, including railroad protective liability.
• Environmental: environmental legal liability, contractors pollution, contractors professional and pollution (CP3), transportation pollution, storage tank and products pollution, typically up to $25 million. See pollution liability insurance and the pollution exclusion.
• Professional lines: accountants, architects and engineers, lawyers, financial services, healthcare-related and miscellaneous errors and omissions, up to $25 million, admitted or non-admitted.
• Management liability: mostly excess D&O, financial institutions D&O and E&O, fiduciary and employment practices liability for public companies and mid-size to large banks and insurers, with $25 million capacity. See Directors and officers (D&O) insurance explained.
• Other lines: cyber, property, marine, energy and construction (inland marine), product recall, a physicians medical malpractice program and a real estate appraisers liability program.

Who it insures

This is a middle-market and large-account market, not a small business carrier. Primary casualty targets companies with $5 million to $2 billion in sales and moderate to high hazards, preferring severity exposures with real loss control over high-frequency classes: manufacturers, importers and distributors, contractors, real estate owners and managers, and hospitality, including restaurants, bars and hotels. Excess casualty goes up to Fortune 1000 companies with construction, transportation, rail and products exposures. Management liability focuses on public companies and financial institutions.

Many of these risks sit in the E&S market, where Aspen Specialty can use non-admitted forms and rates. That flexibility is the point for hard-to-place risks, but surplus lines policies are generally not backed by state guaranty funds.

How to buy

You reach Aspen only through a broker: a retail broker for admitted excess, professional and management liability, or a wholesale broker for surplus lines. With the Sompo transition under way, ask your broker whether a new or renewal policy will be issued by an Aspen company or a Sompo company such as Endurance, since that changes the insurer name on your certificates and the rating behind it. Aspen does not quote online and offers no small business products.

Claims

Claims on policies issued by Aspen companies are reported through Sompo's Aspen legacy claims page, using the online form and selecting the U.S. policy prefix (for example, casualty, environmental, professional liability, management liability, property or marine and construction), or through your broker, who then becomes the main contact. Sompo does not list a separate phone number for Aspen legacy claims. Policies issued by Sompo companies use Sompo's own claims process, so check the issuing company on your declarations page before you report. Aspen describes its excess casualty claims handling as integrated with underwriting, with underwriters in New York, Chicago, Dallas, Atlanta, San Francisco, London and Bermuda.

Financial strength and ratings

On September 10, 2026, AM Best upgraded the Financial Strength Rating of Aspen American Insurance Company, Aspen Specialty Insurance Company, Aspen Insurance UK and Aspen Bermuda to A+ (Superior) from A (Excellent), stable outlook, and their issuer credit ratings to "aa-" from "a", positive outlook. AM Best tied the upgrade to the strongest balance sheet of Sompo Japan Insurance, net worth maintenance agreements and the Aspen companies' integration with Sompo after a restructuring. Before the deal, AM Best had affirmed Aspen at A (Excellent) in August 2025.

Aspen's own financial reporting ended with the delisting of its common shares; Insurance Business reported that Aspen had a combined ratio of 87.9% for 2024 and more than $4.6 billion of annual gross written premium when Sompo agreed to buy it.

Strengths and weaknesses

Aspen brings deep specialty casualty and professional lines underwriting, and since September 2026 it carries the A+ rating that comes with Sompo Japan's backing. It is also a company in transition, with policies, claims and branding moving between two names.

• Strengths: Large capacity in excess casualty, environmental, professional and management liability (often $25 million). Both admitted and surplus lines paper in the U.S. AM Best upgraded the U.S. carriers to A+ in September 2026. Specialist niches such as railroad liability and contractors pollution.
• Weaknesses: Ownership changed twice in seven years (Apollo in 2019, Sompo in 2026), and the business is moving to the Sompo brand, so issuing companies, forms and contacts may change at renewal. Aspen legacy claims are handled through an online form with no published phone line. High minimum premiums (generally $50,000 for primary casualty) and no small business appetite.

How to contact Aspen Insurance