Table of Contents The following table details the results of operations for Specialty. Gross written premiums, excluding third party captives, for Specialty increased $181 million in 2019 as compared with 2018 driven by strong retention and rate. Net written premiums for Specialty increased $104 million in 2019 as compared with 2018. The increase in net earned premiums was consistent with the trend in net written premiums. Core income increased $42 million in 2019 as compared with 2018 primarily due to higher net investment income driven by limited partnership and common stock returns partially offset by lower favorable net prior year loss reserve development. The combined ratio of 90.2% increased 2.0 points in 2019 as compared with 2018. The loss ratio increased 1.6 points driven by lower favorable net prior year loss reserve development. Net catastrophe losses were $15 million, or 0.5 points of the loss ratio, for 2019, as compared with $26 million, or 1.0 point of the loss ratio, for 2018. The expense ratio increased 0.4 points in 2019 as compared with 2018 driven by higher employee costs. Favorable net prior year loss reserve development of $92 million and $150 million was recorded in 2019 and 2018. Further information on net prior year loss reserve development is in Note E to the Consolidated Financial Statements included under Item 8. 2019 Compared with 2018 Years ended December 31 (In millions, except ratios, rate, renewal premium change and retention) 2019 2018 Gross written premiums $ 6,900 $ 6,904 Gross written premiums excluding third party captives 3,015 2,834 Net written premiums 2,848 2,744 Net earned premiums 2,773 2,732 Net investment income 556 439 Core income 671 629 Other performance metrics: Loss and loss adjustment expense ratio 57.5 % 55.9 % Expense ratio 32.5 32.1 Dividend ratio 0.2 0.2 Combined ratio 90.2% 88.2% Rate 5% 2% Renewal premium change 6 5 Retention 87 85 New business $ 367 $ 353 32