The reconciliation of such measures to the most comparable GAAP figures is included in our earnings release, financial supplement and earnings presentation, all of which are available on our website at aig.com. Demand for expertise in property and energy, trade credit, and political risk insurance is increasing as clients navigate heightened uncertainty related to shifting trade policies. We had an excellent start to the year and have been very focused on advancing our strategic investments and delivering on the ambitious 3-year guidance that we provided at Investor Day in 2025. Net premiums earned growth is expected to benefit AIG in the back half of 2026 and as we enter 2027.
All three business segments performed exceptionally well, supported by our recent strategic transactions, our differentiated reinsurance strategy, and profitable organic growth that's in line with market peers. We grew net premiums written 11% in the Q1, benefiting from the restructuring of our related reinsurance treaties and organic growth, along with meaningful improvement in the expense ratio, which decreased 410-basis points. The accident year combined ratio as adjusted improved 570-basis points to 89.9%. Shifting back to overall General Insurance financial results, the expense ratio was 29.3%, an improvement of 120-basis points year-over-year.
The accident year combined ratio as adjusted was 86.6%, an improvement of 120-basis points year-over-year. The calendar year combined ratio was 87.3%, an improvement of 850-basis points year-over-year. Adjusted after-tax income per diluted share was $2.11, an increase of 80% year-over-year. Turning to capital management, during the quarter, we returned $760 million of capital to shareholders, including $519 million of share repurchases and $241 million of dividends.