Thank you, Dhruv, and good morning, good afternoon, everyone. Thank you for joining our first quarter 2024 results call. As you can hear, I have a rather croaky voice today, so I apologize in advance, but the great news is our results are better than my voice.
I'm really pleased to be able to say that 2024 is off to a strong start. We delivered our sixth consecutive quarter of positive underwriting results, improved the quality of our earnings and took action to further strengthen our balance sheet. The performance momentum from 2023 has continued with strong year-over-year performance. We are executing on our ambition to deliver consistent and stable earnings that create long-term shareholder value. Our strong results and strategic actions taken this quarter move us closer to our longer-term ambition of becoming a best-in-class insurer/reinsurer.
Before sharing the key messages relating to our results, I want to recap on four developments from the quarter within our key messages on Slide 5. Firstly, I would like to highlight the liability management exercise we completed recently. This has further improved the quality and strength of our balance sheet and area that we highlighted in Q4 that we would focus on. We announced 3 debt transactions in late March, including our debut -- debt issuance of $400 million. These transactions were aimed at refinancing $400 million of 2026 legacy senior notes and redeeming $115 million of legacy 2025 senior notes, all were successfully executed.
The new debt instrument will be capital accretive under the rating agency and regulated capital models and will increase our capital levels by a further $300 million on a net basis. This increase in capital equates to an approximately 20 point improvement in our Q4 '23 BSCR ratio, which already stands at 255% before this. Our capital levels have never been stronger. Additionally, the redemption of the $115 million '25 senior notes will reduce our financial leverage by around 2.5 points. These transactions, together, were designed to simplify and optimize our capital structure and complete another part of our repositioning of the group.
Secondly, and as we previously communicated, we identified a material weakness in our internal controls over financial reporting in Quarter 3, 2023. As a reminder, the material weakness was in respect to a misstatement of our quarterly premiums during the first half of '23. I am pleased to say that this has now been fully remediated as of Quarter 4, 2023. Thirdly, we obtained new ratings from Moody's ahead of our debt offering. They have assigned us an A3 financial strength rating, further validating the progress we have made in improving our results and strengthening our balance sheet. As a reminder, we have financial strength ratings from AM Best, S&P and Fitch. And this year, S&P, Fitch and AM Best affirmed our financial strength ratings as stable.
And finally, I want to highlight the loss portfolio transaction we announced yesterday. This transaction covers approximately $400 million of workers' comp reserves linked solely to the business we already exited at 1/1 this year. Given the historical poor performance of this specific book, we felt it was the right decision to reduce future uncertainty now as part of our balance sheet improving the work. We have entered into a transaction with Enstar, which is subject to regulatory approval. This will further improve the quantum and quality of our reserve margin.
Turning back now to our Q1 results. We are very pleased to report a strong first quarter with a combined ratio of 91.4% for our core business, net income of $91 million and diluted book value per share growth of 2%. Importantly, our Q1 performance is within the updated medium-term ROE guidance range of 12% to 15%.
Beginning with our strong underwriting result for the quarter, our headline combined ratio of 91.4% for our core business was an improvement of 5% versus prior year on a like-for-like basis, excluding the loss portfolio transfer transaction we announced in the first quarter of 2023. The combined ratio has been supported by both loss and expense ratio improvements with the loss ratio improving 5 points, of which, importantly, 3 points came from attritional loss ratio improvement. We recorded no cat losses in the first quarter compared to $7 million last year and have no material exposure related to the Baltimore's Key bridge.
On an accident year basis, the combined ratio also saw an improvement and was down by around 4 points to 92.9%. Additionally, on a consolidated basis, this quarter marks the 12th consecutive quarter of favorable prior year development, providing strong evidence of our prudent approach to reserving. Our other underwriting expense ratio for core business also decreased 1.4 points versus Q1 last year as we realized the benefits from a cost-saving program. Combined, these improvements are important proof points of the actions we have and are taking to drive better underwriting performance.
Turning to our investment result, which continues to be strong in quarter 1. Net investment income of $79 million reflects the strong rate performance in the first quarter, continued optimization work by the team and rotation into high-quality spread products. Our portfolio continues to perform well. And again, we saw no defaults across our fixed income portfolio this quarter. Overall, our investment strategy remains unchanged, and we continue to operate a fixed income portfolio with an average credit rating at AA.
Turning now to our distribution strategy and consolidated MGAs, which have delivered strong results. Our distribution strategy remains important to us, and we have continued to onboard new MGA underwriting partners in line with our intention to partner as a paper and capacity provider without taking an equity stake. We added a total of three new MGA partners in the first quarter and expanded our relationship with two existing partners. Since the end of the quarter, we have also entered into two further new partnerships. This momentum we are building should bear fruit as we go through the year and emerge from the impact of the underwriting decisions we have taken to improve the underwriting profits.
We continue to rationalize our equity stakes in the first quarter, closing the previously announced sale of Corvus and writing off a small investment. This brings our total holdings to 24 at the end of the first quarter, down from 36 at the beginning of 2023.
Moving on to our consolidated MGA's stand-alone performance. Service revenues were up 3% on prior year, while service margin increased by 1 point to 30%, generating net service fee income of $20 million, up 8% year-on-year. Despite the strong underlying performance, we continue to believe that the actual economic value is significantly higher than the carrying value of these assets and is not fully reflected in SiriusPoint's share price.
So in summary, 2024 is off to a strong start. Our aim is to keep that going. We are focused on improving the returns of the business, targeting a 12% to 15% return on equity in the medium term. Q1 performance shows we are on track. With these remarks, I will pass it over to Steve, who will take you through the financials.