Hamilton Insurance Group, Ltd.

Gross premiums written increased by $208.6 million, or 15.9%, from $1.3 billion for the year ended December 31, 2024 to $1.5 billion for the year ended December 31, 2025, primarily driven by growth in both new and existing business in casualty, specialty and property insurance classes.

Gross premiums written increased by $202.9 million, or 18.4%, from $1.1 billion for the year ended December 31, 2023 to $1.3 billion for the year ended December 31, 2024, primarily driven by growth in both new and existing business and improved pricing in casualty and property insurance classes and specialty reinsurance and insurance classes.

Net premiums earned increased by $168.4 million, or 19.0%, from $886.9 million for the year ended December 31, 2024 to $1.1 billion for the year ended December 31, 2025. The increase was primarily driven by growth in our casualty, specialty and property insurance classes. Casualty insurance growth was primarily driven by U.S. excess and surplus lines, mergers & acquisitions and professional lines; specialty insurance growth was primarily driven by accident & health and marine & energy; property insurance growth was primarily driven by property binder business; and specialty reinsurance growth was primarily driven by war and terrorism and surety reinsurance.

Net premiums earned increased by $183.4 million, or 26.1%, from $703.5 million for the year ended December 31, 2023 to $886.9 million for the year ended December 31, 2024. The increase was driven by growth in our specialty, casualty and property insurance classes, in addition to growth in the specialty reinsurance class. Specialty insurance growth was primarily driven by accident & health, fine art & specie, political violence, and marine & energy; casualty insurance growth was primarily driven by U.S. excess and surplus lines, professional lines, and cyber, partially offset by a decrease in mergers & acquisitions; property insurance growth was primarily driven by property binders and D&F; and specialty reinsurance growth was primarily driven by surety reinsurance and treaty reinsurance.

Third party fee income decreased by $4.3 million, or 26.3%, from $16.3 million for the year ended December 31, 2024 to $12.0 million for the year ended December 31, 2025. The decrease was primarily due to a decrease in syndicate management fees. Effective July 1, 2025, the management of the third party syndicate was novated from Hamilton Managing Agency to another Lloyd's managing agency. This ended the Company's management of third party syndicates.

Third party fee income increased by $6.6 million or 68.5%, from $9.7 million for the year ended December 31, 2023 to $16.3 million for the year ended December 31, 2024. The increase was primarily due to favorable terms of a renewed syndicate management arrangement and an increase in consortium fees.

Year Ended December 31, 2025 versus Year Ended December 31, 2024

Attritional loss ratio - current year for the year ended December 31, 2025 was 54.0% compared to 53.5% for the year ended December 31, 2024, an increase of 0.5 percentage points.

Attritional loss ratio - prior year for the year ended December 31, 2025 was a favorable 2.8% compared to a favorable 0.4% for the year ended December 31, 2024, a decrease of 2.4 percentage points. The favorable attritional loss ratio - prior year for the year ended December 31, 2025 was primarily driven by favorable development in property, specialty and casualty insurance classes, partially offset by modest unfavorable development in casualty reinsurance classes. In addition, casualty business protected by the LPT discussed in Note 7, Reinsurance, benefited from favorable development in the underlying reserves of $2.5 million, which was partially offset by a change in the deferred gain of $0.8 million, for a total net positive earnings impact of $1.7 million.

Catastrophe losses - current year and prior year were $30.2 million and $26.7 million for the years ended December 31, 2025 and 2024, respectively. Catastrophe losses for the year ended December 31, 2025 were driven by the California wildfires ($29.0 million) and severe convective storms ($1.6 million), partially offset by favorable prior year development of $0.4 million. Catastrophe losses for the year ended December 31, 2024 were driven by Hurricane Helene ($19.6 million), Hurricane Milton ($12.8 million), and Hurricane Debby ($1.5 million), partially offset by favorable prior year development of $7.2 million.

Year Ended December 31, 2024 versus Year Ended December 31, 2023

Attritional loss ratio - current year for the year ended December 31, 2024 was 53.5% compared to 53.2% for the year ended December 31, 2023, an increase of 0.3 percentage points. The increase included a specific large loss of $11.8 million arising from the Baltimore Bridge collapse.

Attritional loss ratio - prior year for the year ended December 31, 2024 was a favorable 0.4% compared to a favorable 3.5% for the year ended December 31, 2023, an increase of 3.1 percentage points. We experienced favorable prior year development for the year ended December 31, 2024 of $3.4 million, primarily driven by property insurance and reinsurance classes, partially offset by unfavorable development in specialty insurance classes, impacted by two large losses, and casualty insurance, impacted by one specific large loss.

Catastrophe losses - current year and prior year were $26.7 million and $12.6 million for the years ended December 31, 2024 and 2023, respectively. Catastrophe losses for the year ended December 31, 2024 were driven by Hurricane Helene ($19.6 million), Hurricane Milton ($12.8 million), and Hurricane Debby ($1.5 million), partially offset by favorable prior year development of $7.2 million. Catastrophe losses for the year ended December 31, 2023 were driven by the Vermont floods ($4.5 million), Hurricane Idalia ($2.9 million), Hawaii wildfires ($2.8 million), and other wind events ($0.5 million), in addition to unfavorable prior year development of $1.9 million.

The acquisition cost ratio for the year ended December 31, 2025 was 26.2%, compared to 24.5% for the year ended December 31, 2024, an increase of 1.7 percentage points. The increase was primarily driven by casualty insurance classes and specialty reinsurance classes, primarily due to higher profit commission costs on certain lines of business and a change in business mix.

The acquisition cost ratio for the year ended December 31, 2024 was 24.5% compared to 26.5% for the year ended December 31, 2023, a decrease of 2.0 percentage points. The decrease was primarily driven by specialty, casualty and property insurance classes as a result of a change in business mix, reduced profit commission costs and favorable ceded commission income.

Other Underwriting Expenses and Other Underwriting Expense Ratios

Other underwriting expenses are general and administrative costs incurred by our reportable segments.

Other underwriting expenses were $167.2 million for the year ended December 31, 2025, an increase of $18.4 million, or 12.4%, compared to $148.8 million for the year ended December 31, 2024. The increase was primarily driven by an increased headcount as we continued to build out underwriting teams supporting the corresponding increase in premium volumeand an increase in certain variable performance based compensation costs.

Other underwriting expenses were $148.8 million for the year ended December 31, 2024, an increase of $21.4 million, or 16.8%, compared to $127.4 million for the year ended December 31, 2023. The increase was primarily driven by increases in headcount as we continued to build out underwriting teams supporting the corresponding increase in premium volume, and certain growth related professional and IT costs.

The other underwriting expense ratios for the years ended December 31, 2025, 2024 and 2023 decreased over the same period at 14.7%, 14.9% and 16.7%, respectively, driven by growth in the premium base, partially offset by an increase in the underlying costs and a decrease in third party management fees.