However, premium reduction was largely driven by exits in certain programs like cyber and workers’ compensation and adjusting for those, premiums were down 7% for the core business. The reduction in premium demonstrates the decisive actions we have taken to prioritize underwriting profitability and to ensure we are closing the financial performance gap to operate at best-in-class levels. We do expect to pivot to growth in 2025. Core MGA revenues grew 3% on prior year to $66 million and were driven mainly by growth from Armada, IMG, and Arcadian. Margins improved by 1.4 points to a strong 30% resulting in our MGA net services fee income increasing to $20 million for the quarter and was driven by better margins at both Armada and IMG. Total investment result for the quarter was strong at $80 million, this was driven by $79 million of net investment income, which is up by $17 million, compared to the prior quarter as the derisked portfolio continues to benefit from rate increases.
Unrealized and realized gains, including from related party investment funds, were 1 million. Net income of $91 million is lower compared to the prior year quarter of $132 million, which included a one-off benefit of 80 million post-tax relating to the loss portfolio transfer announced in March of last year. On a like-for-like basis, excluding the benefit of the loss portfolio transfer, net income was up $44 million. Other items impacting income included $4 million of foreign exchange gains and a $16 million impact from mark to market on liability classified capital instruments. Common shareholders’ equity grew by 4% during the quarter, supported by strong earnings. Adjusting for AOCI, common shareholders’ equity growth was 5% in the quarter.
Moving on to Slide 9. I will focus on the rate trends, including 4/1 renewals. We saw an average rate change at around 4% across our portfolio, excluding the North American program business. Rate change was mainly driven by the U.S. Casualty and non-US Property portfolio. Non-US Property saw 4% rate increase while rates in the US Casualty increased by 3%. Accident and Health rates were up around 5%, while rates in the International business were up 4%. Moving to the topic of renewals. Only 6% of our business renews in April, excluding North American Program Business. We experienced an average rate change at around 5% across the portfolio, excluding North America Program Business. Next, Slide 10 shows the year-to-date changes in combined ratio for our core business and breaks the movements into individual subcomponents.
Our headline combined ratio for the corn business was 80.5% in the first quarter of 2023 and benefited from 16.3 points of reserve releases linked to the LPT transaction. Likewise, we benefited by 0.3 points from the LPT in the first quarter of 2024 related to the recognition of the deferred gain-like combined ratio of 91.4%. Adjusting for these LPT-related benefits, we saw 5.1 points of improvement on a like-for-like basis. The improvement in the combined ratio for the core business was driven mainly by lower attritional and cat losses compared to the same period of the prior year. The core attritional loss ratio was at 59.7%, down 2.6 points on the previous year period while we had no cats in the first quarter compared to $7 million last year for the core business.
On Slides 11 and 12, we look at the investment portfolio investment result. We delivered strong net investment income of $79 million increased our overall asset duration to 2.9 years from 2.8 years versus full-year 2023 and locked in attractive reinvestment yields in excess of 4.5% on our investments during the quarter. We continue to rotate our portfolio during the first quarter, investing over $300 million from short-term investments in treasuries into high grade corporates and structured credit. We continue to benefit from higher rates. Overall, our investment strategy remains unchanged and focused on maintaining a high-quality fixed-income portfolio. 75% of our investment portfolio is now fixed income, of which 98% is investment grade with an average credit rating unchanged at AA.
We did not experience any defaults in our fixed-income portfolio during the quarter. P&L volatility is significantly lower and has helped given 93% of the fixed-income portfolio is now designated as available for sale, up from 90% at Q4 2023 and none at year-end 2021. Moving on to Slide 13, which looks at our balance sheet. Our balance sheet is strong, ending the quarter with $2.4 billion of common shareholders’ equity, which is up 4% in the quarter driven by the growth in net income. Total capital, including debt, stood at $3.4 billion. We lowered our debt to total capital ratio to 22.8%, which is within our target range. Debt leverage improved by 1 point and asset leverage is stable at 3.2x. As a result of the debt actions mentioned earlier, we expect debt leverage to improve by a further 2.5 points.
With this, we conclude the financial section of our presentation. Our first quarter results were strong and demonstrated another quarter of stable, consistent and improving results. We expect to build on this performance and aim to deliver a 12% to 15% return on average common equity in the medium term. I would like to thank you again for your time this morning. For any questions, please contact our Investor Relations team at investor.relations@siriuspt.com. I now turn the call back over to the operator.
Operator: Thank you. This will conclude today’s conference. You may disconnect your lines at this time and thank you for your participation.
End of Q&A:
