$16.7 million, or 6.5%, to $272.2 million from $255.5 million for the comparable 2024 period. Net written premiums for the year ended December 31, 2025 increased by $82.2 million, or 7.5%, to $1,175.7 million from $1,093.5 million for the comparable 2024 period.
The increases in direct written premiums and net written premiums are a result of rate increases. For the year ended December 31, 2025, average written premium per policy increased 8.1%, 4.6% and 9.7% in Private Passenger Automobile, Commercial Automobile and Homeowners lines, respectively, compared to the same period in 2024.
Net earned premiums for the quarter ended December 31, 2025 increased by $24.1 million, or 9.0%, to $293.2 million from $269.1 million for the comparable 2024 period. Net earned premiums for the year ended December 31, 2025 increased by $128.3 million, or 12.7%, to $1,139.0 million from $1,010.7 million for the comparable 2024 period. The increase in net earned premium is the result of prior year growth in direct written premiums earning into top-line results.
For the quarter ended December 31, 2025, losses and loss adjustment expenses incurred increased by $14.7 million, or 7.6%, to $207.7 million from $193.0 million for the comparable 2024 period. For the year ended December 31, 2025, losses and loss adjustment expenses incurred increased by $80.6 million, or 11.2%, to $797.2 million from $716.6 million for the comparable 2024 period. The increase in losses is driven by our larger policy counts and current market conditions, specifically inflationary impacts on our Private Passenger Automobile book of business.
Loss, expense, and combined ratios calculated for the quarter ended December 31, 2025 were 70.8%, 28.6%, and 99.4%, respectively, compared to 71.7%, 30.2%, and 101.9%, respectively, for the comparable 2024 period. The decrease in loss and expense ratios is driven by the increase in net earned premiums. Loss, expense, and combined ratios calculated for the year ended December 31, 2025 were 70.0%, 29.0%, and 99.0%, respectively, compared to 70.9%, 30.2%, and 101.1%, respectively, for the comparable 2024 period.
Total prior year favorable development included in the pre-tax results for the quarter ended December 31, 2025 was $11.4 million compared to $13.0 million for the comparable 2024 period. Total prior year favorable development included in the pre-tax results for the year ended December 31, 2025 was $44.6 million compared to $51.9 million for the comparable 2024 period. Included within prior year development for the year ended December 31, 2024 was $8.6 million related to a restructuring of the Massachusetts Property Insurance Underwriting Association.
Net investment income for the quarter ended December 31, 2025 increased by $2.1 million, or 14.3%, to $16.9 million from $14.8 million for the comparable 2024 period. Net investment income for the year ended December 31, 2025 increased by $7.0 million, or 12.6%, to $62.7 million from $55.7 million for the comparable 2024 period. The increase is a result of increases in interest rates on our fixed maturity portfolio compared to the prior year. Net effective annualized yield on the investment portfolio was 4.2% for the quarter ended December 31, 2025 compared to 4.0% for the comparable 2024 period. Net effective annualized yield on the investment portfolio was 4.0% for the year ended December 31, 2025 compared to 3.9% for the comparable 2024 period. The investment portfolio’s duration on fixed maturities was 3.9 years at December 31, 2025 compared to 3.5 years at December 31, 2024.
Non-GAAP Measures
Management has included certain non-GAAP financial measures in presenting the Company’s results. Management believes that these non-GAAP measures are useful to explain the Company’s results of operations and allow for a more complete understanding of the underlying trends in the Company’s business. These measures should not be viewed as a substitute for those determined in accordance with generally accepted accounting principles (“GAAP”). In addition, our definitions of these items may not be comparable to the definitions used by other companies.