Hamilton Insurance Group, Ltd.

Gross Premiums Written

Gross premiums written increased by $72.9 million, or 19.7%, from $370.0 million for the three months ended March 31, 2025 to $442.9 million for the three months ended March 31, 2026, primarily driven by growth in both new and existing business in casualty and specialty insurance classes.

Net Premiums Earned

Net premiums earned increased by $50.2 million, or 20.9%, from $240.6 million for the three months ended March 31, 2025 to $290.8 million for the three months ended March 31, 2026. The increase was primarily driven by growth in our specialty insurance and reinsurance classes and casualty insurance classes. Specialty insurance growth was primarily driven by accident & health, fine art & specie and marine & energy; specialty reinsurance growth was primarily driven by surety reinsurance and treaty reinsurance; and casualty insurance growth was primarily driven by U.S. excess and surplus lines and professional lines.

Third party fee income decreased by $1.8 million, from $4.3 million for the three months ended March 31, 2025 to $2.5 million for the three months ended March 31, 2026. 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.

Attritional loss ratio - current year for the three months ended March 31, 2026 was 54.9% compared to 52.1% for the three months ended March 31, 2025, an increase of 2.8 percentage points. The increase was primarily driven by a change in business mix, including more specialty insurance business.

Attritional loss ratio - prior year for the three months ended March 31, 2026 was an unfavorable 1.4% compared to a favorable 3.6% for the three months ended March 31, 2025, an increase of 5.0 percentage points. The unfavorable attritional loss ratio - prior year for the three months ended March 31, 2026 was primarily driven by additional loss information in relation to the Baltimore Bridge collapse. Inaddition, casualty business protected by the LPT discussed in Note 6, Reinsurance, benefited from favorable development in the underlying reserves of $0.1 million and a change in the deferred gain of $0.2 million, for a total net positive earnings impact of $0.3 million.

Catastrophe losses - current year and prior year were $Nil for the three months ended March 31, 2026. Catastrophe losses for the three months ended March 31, 2025 were as a result of the California wildfires of $29.0 million.

The acquisition cost ratio for the three months ended March 31, 2026 was 27.9%, compared to 26.1% for the three months ended March 31, 2025, an increase of 1.8 percentage points. The increase was primarily driven by specialty insurance and reinsurance classes, due to a change in business mix.

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 $41.3 million for the three months ended March 31, 2026, an increase of $5.7 million, or 15.9%, compared to $35.6 million for the three months ended March 31, 2025. The increase was primarily driven by an increase in personnel costs and the impact of a strengthening British Pound against the U.S. Dollar.

The other underwriting expense ratio for the three months ended March 31, 2026 and 2025 increased modestly from 13.0% to 13.3%, driven by an increase in the underlying costs and a decrease in third party fee income, partially offset by growth in the premium base.