Hamilton Insurance Group, Ltd.

Gross premiums written increased by $67.6 million, or 8.0%, from $840.6 million for the six months ended June 30, 2025 to $908.2 million for the six months ended June 30, 2026, primarily driven by growth in both new and existing business in casualty reinsurance classes, partially offset by a decrease in property reinsurance classes as a result of lower reinstatement premiums and rate decreases.

Net premiums earned increased by $46.8 million, or 9.1%, from $516.3 million for the six months ended June 30, 2025 to $563.1 million for the six months ended June 30, 2026, primarily driven by new business and volume growth in our casualty reinsurance classes, partially offset by a decrease in our property reinsurance classes as a result of lower reinstatement premiums and rate decreases. The increase in casualty reinsurance was primarily driven by general liability lines.

Third party fee income is generated by certain performance and management fees recognized by Ada Capital Management Limited for services provided to Ada Re, Ltd. and increased by $4.8 million, from $1.5 million for the six months ended June 30, 2025 to $6.3 million for the six months ended June 30, 2026.

Attritional loss ratio - current year for the six months ended June 30, 2026 was 54.9% compared to 53.0% for the six months ended June 30, 2025, an increase of 1.9 percentage points. The increase was primarily driven by a change in business mix, including more proportional casualty reinsurance business.

Attritional loss ratio - prior year for the six months ended June 30, 2026 was an unfavorable 4.1% compared to a favorable 0.1% for the six months ended June 30, 2025, an increase of 4.2 percentage points. The unfavorable attritional loss ratio - prior year for the six months ended June 30, 2026 was primarily driven by additional loss information in relation to certain large losses, including the Baltimore Bridge collapse, and unfavorable development in certain casualty reinsurance classes, partially offset by favorable development in property reinsurance classes.

Catastrophe losses - current year and prior year were $16.2 million and $121.9 million for the six months ended June 30, 2026 and 2025, respectively. Catastrophe losses for the six months ended June 30, 2026 were driven by the Middle East conflict ($12.0 million), in addition to unfavorable prior year development of $4.2 million. Catastrophe losses for the six months ended June 30, 2025 were driven by the California wildfires ($130.7 million) andsevere convective storms ($8.3 million), partially offset byfavorable prior year development of $17.1 million.

The acquisition cost ratio for the six months ended June 30, 2026 was 22.8%, compared to 21.5% for the six months ended June 30, 2025, an increase of 1.3 percentage points. The increase was driven by a change in business mix, including more proportional business written in our casualty reinsurance classes, partially offset by an increase in ceded commission income.

Other underwriting expenses for the six months ended June 30, 2026 were $22.2 million, a decrease of $8.4 million, or 27.3%, compared to $30.6 million for the six months ended June 30, 2025. The decrease was primarily driven by Bermuda substance-based tax credits, partially offset by an increase in personnel costs.

The other underwriting expense ratio for the six months ended June 30, 2026 and 2025 decreased from 5.6% to 2.8%, driven by the Bermuda substance-based tax credits, certain performance based management fees recognized by Ada Capital Management Limited for services provided to Ada Re, Ltd. and growth in the premium base.