Sompo business insurance

Overview

Sompo is the international commercial insurance and reinsurance business of Japan's Sompo Holdings, run from Bermuda by Sompo International Holdings Ltd. and now marketed simply as Sompo (its commercial insurance arm is styled Sompo Commercial P&C Insurance). Its U.S. group was ranked No. 28 among U.S. business insurers by 2025 commercial lines direct premiums written, with $4.66 billion, based on NAIC market share data, or about 0.96% of the national commercial market. More than half of that is other liability (general, excess and professional liability). Its only national top-10 position is aircraft insurance, where it ranks fifth.

Most U.S. policies are issued by companies still carrying the Endurance name: Endurance American Insurance Company, Endurance Assurance Corporation, Endurance Risk Solutions Assurance Co. and the surplus lines carrier Endurance American Specialty Insurance Company. The group also includes Sompo America Insurance Company and Sompo America Fire & Marine (the former U.S. arm of Sompo Japan), the surety companies Lexon and Bond Safeguard, and American Agri-Business Insurance Company, which writes federally backed crop insurance as AgriSompo. Crop premium is not counted in the commercial lines total above, which is why the group's all-lines figure is much larger, at $7.44 billion.

Sompo sells only through brokers and agents. James Shea is CEO of Sompo P&C, the group's global property and casualty umbrella, and of Sompo International; Christopher Sparro runs North America.

History

Sompo's Japanese parent, listed in Tokyo as Sompo Holdings (8630), traces its history back more than 135 years. Its U.S. commercial business mostly came through one deal. On March 28, 2017, Sompo completed its $6.3 billion purchase of Endurance Specialty Holdings, a Bermuda insurer and reinsurer led by John Charman, and created Sompo International to combine Endurance with Sompo's existing overseas commercial and reinsurance operations. Sompo America was rebranded under Sompo International. Endurance's crop business, ARMtech, kept its own brand at first and is now AgriSompo. AM Best upgraded the Endurance companies to A+ (Superior) from A (Excellent) when the deal closed, citing Sompo's backing through a net-worth maintenance agreement.

In 2025 Sompo Holdings set up Sompo P&C to manage its property and casualty businesses outside Japan, with Shea as CEO. On August 27, 2025, Sompo agreed to buy Aspen Insurance Holdings for about $3.5 billion ($37.50 a share). Regulatory approvals arrived in February 2026 and the deal closed on February 24, 2026; Aspen's common shares left the NYSE and its business is moving to the Sompo brand. Aspen's 2025 U.S. premium is shown separately under Aspen Insurance because the NAIC data predates the closing. On July 7, 2026, Sompo agreed to buy Service Insurance Companies, a monoline workers' compensation insurer founded in 1982, to make it the flagship of Sompo's U.S. comp business; terms were not disclosed and closing is subject to regulatory approval. See when your insurer is sold or merges: what happens to your policy for what an ownership change means for existing policies.

Business insurance products

Casualty. Primary retail casualty with multi-line programs for real estate and hospitality, manufacturing, life sciences, technology and financial and professional services; primary casualty on an excess and surplus lines basis through appointed wholesalers; and excess casualty in retail, E&S and a dedicated transportation unit for fleets. See umbrella vs excess liability for how those layers fit together.

Property. Commercial specialty property for midsize through large accounts, on a primary, ground-up or excess basis, plus E&S property with catastrophe capacity.

Professional and financial lines. Primary and excess management liability (D&O and related lines), Sompo Pro for primary and excess professional liability, cyber and network risk, environmental coverage, private equity and M&A programs, and package policies for professional services firms.

Surety. Contract, commercial and transactional bonds through four companies (Endurance Assurance, Endurance American, Lexon and Bond Safeguard) in all 50 states and Puerto Rico. Sompo says it is a top-15 U.S. surety, with a combined U.S. Treasury listing of $425 million, a small contractor program, SBA bond capability and a digital hub for commercial bonds. See surety bonds explained: how they differ from insurance.

Specialty and crop. Aviation (the source of the No. 5 aircraft rank), marine, energy and construction, plus AgriSompo's crop insurance for farmers. Worldwide, Sompo also writes reinsurance as SompoRe.

Who it insures

Sompo's U.S. target is the middle market and up, placed by brokers. Its published capability list covers construction, energy, financial institutions, healthcare, life sciences, manufacturing and processing, marine, mercantile, private equity, real estate, technology and transportation.

One niche stands out. The U.S. Asian Risk Solutions team insures Japanese, South Korean and other Asian companies operating in the U.S., Canada and Mexico, from new entrants to established manufacturers and service firms. Each client gets a dedicated client relationship executive who coordinates underwriting, claims and risk control, and Sompo reports a 95% retention rate in that book. In that segment Sompo competes most directly with the other Japanese-owned groups, Tokio Marine and MSIG USA.

Small businesses generally reach Sompo only indirectly, through a wholesale broker's E&S placement or a surety bond.

How to buy

Through a broker. Sompo's U.S. insurance practice works with national and regional retail brokers and with appointed wholesale brokers for E&S; its surety team works through independent agents and brokers nationwide. There is no online quoting for buyers. Expect a full underwriting submission with exposures, loss runs and, for casualty, details of contracts, products and fleet. The website's contact form takes new business inquiries by country, state and product.

Sompo lists more than 30 U.S. office locations, including New York, Purchase (New York), Chicago, Atlanta, Dallas, Houston, Los Angeles, San Francisco, Boston, Charlotte and St. Louis, plus AgriSompo offices in farm states.

Claims

U.S. insurance claims are reported at 877-676-7575 or by email to [email protected]. Policies issued by Aspen before the merger have a separate legacy claims process on Sompo's site, so check which company issued your policy before you report. Sompo handles claims with an in-house team that it describes as working alongside underwriting and risk control, and its risk control team provides loss prevention services to casualty and property clients.

Financial strength and ratings

Sompo's site, as of October 2026, lists A+ (Superior, stable) from AM Best for all of its U.S. operating companies and A+ from S&P for most of them (Lexon, Bond Safeguard and Sompo America Fire & Marine are not rated by S&P). In March 2026, after the Aspen deal closed, AM Best affirmed the A+ (Superior) financial strength rating of Sompo Japan Insurance and its subsidiaries, moved the issuer credit rating outlooks to positive, and affirmed Sompo International Holdings' "a-" issuer rating. AM Best noted the Aspen purchase may pressure capital but said the group has the buffers to absorb it.

Sompo International does not publish standalone U.S. statutory results on its website; its parent, Sompo Holdings, reported $101 billion of total assets and $27 billion of net premiums written as of March 31, 2025.

Strengths and weaknesses

Sompo combines a top-rated Japanese parent with an Endurance-built specialty platform, and the Aspen deal makes it a much larger global player. The flip side is a business in the middle of integration, with a U.S. footprint that still runs under several legacy company names.

• Strengths: A+ (Superior) from AM Best and A+ from S&P on its main U.S. companies, with AM Best moving outlooks to positive in March 2026. A strong niche serving Asian-owned companies in North America, with dedicated relationship executives. Broad specialty shelf, including a top-15 surety operation and fifth place nationally in aircraft. Admitted and E&S paper for the same lines.
• Weaknesses: Broker-only, with no small-business products. Integration of Aspen (closed February 2026) and the pending Service Insurance Companies deal mean changing teams, forms and legacy claims routes. Policies are issued by Endurance, Sompo America and, for older business, Aspen companies, which can confuse certificate holders. Limited public U.S. financial disclosure compared with a listed U.S. carrier.

How to contact Sompo