Robert Qutub
Analyst · Autonomous Research
Thanks, Kevin, and good morning, everyone. We started the year with another excellent quarter with operating income of $636 million and an annualized operating return on average common equity of 29%. The strong returns in the quarter were driven by superior results across all 3 drivers of profit with underwriting income of $541 million, up 46%, fees of $84 million, up 87% and retained net investment income of $267 million, up 59%.
Year-to-date, we have grown our principal metrics, tangible book value per share plus change in accumulated dividends by 5%. This represents strong earnings that were partially offset by $194 million in retained mark-to-market losses in our investment portfolio. Over time, we expect these losses to accrete back to par. Near term, we are benefiting from higher rates on new investments.
I'll discuss our results in more detail in a moment, but there are a few key takeaways that I would like to highlight. First, as Kevin mentioned, this quarter, you are seeing a full 3-month benefit of Validus in our financial results. Overall, net premiums written were $3.2 billion, up 41% and underwriting income was $541 million, up 46% from Q1 last year.
Second, we reported strong overall underwriting results with a combined ratio of 78% or 75% after adjusting for the impact of purchase accounting. This was a low quarter for catastrophes, with property catastrophe and other property having excellent quarters. The casualty and specialty adjusted combined ratio was 97%, which included an impact of 4 percentage points from the Baltimore bridge collapse, which I will discuss in a moment.
And third, fee income was $84 million on the back of solid growth in our joint ventures and strong performance.
And finally, retained net investment income was a healthy $267 million consensus is building around a higher for longer interest rate environment, which should support strong net investment income for the rest of the year.
In summary, we have built a powerful platform with several distinct sources of income, rewarding our shareholders with secure returns while making us increasingly resilient to catastrophe activity.
Now moving now to our first quarter results and our first driver of profit underwriting. And as we discussed, we had a phenomenally successful 1/1 renewal and retain the combined RenaissanceRe and Validus portfolio according to plan. As a result, gross premium written were up 43% with robust growth across both segments. Net premiums written were up slightly less at 41%, this reflects our decision to purchase some additional ceded protection in our property catastrophe book as part of our gross-to-net strategy as well as some timing differences. We reported strong overall results with an adjusted combined ratio of 75%.
Moving now to our Casualty and Specialty portfolio where gross and net premiums written were up 41% and 45%, respectively, as we incorporated the Validus business onto our platform. As Kevin will explain, we exercised underwriting discipline by growing into attractive areas such as specialty while reducing exposures to areas such as professional liability. Net earned premiums in the Casualty and Specialty were $1.5 billion, up 52%, also driven by Validus. In the second quarter, we are expecting net earned premiums to be about $1.6 billion.
This quarter, we reported an adjusted combined ratio for Casualty and Specialty is 97%, which contained 4 percentage points from the Baltimore bridge collapse. The bridge had an overall net negative impact on our consolidated results of $55 million. On average, we continue to expect a mid-90s Casualty and Specialty combined ratio after adjusting for the impact of purchase accounting.
Moving to our Property segment and starting with Property catastrophe where we reported strong growth driven by renewal of the combined portfolio at attractive rates and terms and conditions. Gross premiums written were up by 44% and net premiums written were up by 30%. We seeded about $277 million or 21% of Property catastrophe business compared to 12% in Q1 last year. Property catastrophe had an excellent quarter with an adjusted combined ratio of 16%, reflecting low losses and 10 percentage points of favorable development. The acquisition expense ratio was up by about 3 percentage points, driven mainly by the impact of purchase accounting adjustments.
Moving now to other property, where gross premiums written were up by 46% and net premiums written were up by 64%, driven mainly by the addition of the Validus portfolio. Net earned premiums in Q1 were $390 million, up 16%. The reductions we made in 2023 and our other property book continued to earn through. In next quarter, we expect other property premiums earned to be about $360 million.
Other property printed excellent results in the quarter with an adjusted combined ratio of 75% and about 11 percentage points of favorable development, predominantly from attritional losses. The other property current accident loss year ratio was 57%, which included a 5 percentage point impact from the Baltimore bridge collapse. Going forward, we continue to expect another property attritional loss ratio in low 50s.
Moving now to fee income in our Capital Partners business, where fee income reached $84 million, up 87% from the comparable quarter. Management fees were $56 million, up 37% from Q1 '23, reflecting increased capital in our joint venture vehicles. Performance fees were $27 million, driven by joint venture growth and strong performance, including favorable development in the quarter. In the second quarter, we expect management fees of around $55 million and performance fees of around $15 million, absent the impact of any large loss events.
Moving now to investments, where retained net investment income was $267 million, up 4% from Q4 and up 60% from a year ago. Treasury rates have consistently ticked up through the year leading to a $194 million retained mark-to-market losses in the quarter. Overall, retained unrealized losses in our fixed maturity investments stand at $189 million or $3.58 per share. We expect this to accrete to par over time.
Our retained yield to maturity was relatively flat at 5.5%, which is slightly higher than our net investment income return of 5.3% in Q1 of this year. We have kept duration stable and in the second quarter, expect retained net investment income will be relatively flat compared to the first quarter. Financial markets are expecting treasury rates to persist around current levels, which should continue to support strong contributions from net investment income in the quarters ahead.
Now turning briefly to expenses. We have already achieved significant synergies from the Validus acquisition. While absolute operating expenses have increased year-over-year due to the acquisition, our operating expense ratio ticked down to 4.3%. We expect the operating expense ratio to stay relatively flat through 2024.
Corporate expenses remain elevated with about $20 million of the $39 million total related to the Validus acquisition. These transaction-related expenses are excluded from operating income and should start to taper off next quarter.
Now finishing with capital management. We are heading into the midyear renewals with a very strong capital position. As we have discussed in the past, RenaissanceRe has a long history of being disciplined stewards of capital, and we remain consistent in our approach to capital management. Our primary focus is optimizing the Validus business by renewing it onto our wholly owned and capital partners' balance sheet. As we complete the integration, we will continue looking for the best opportunities to deploy capital.
And in conclusion, we had another excellent year, another excellent quarter with significant top line growth related to Validus and substantial contributions from each of our 3 drivers of profit. Underwriting income was strong, following a highly successful 1/1 renewal. Management and performance fees were both up significantly driven by underlying portfolio growth and strong performance. And finally, net investment income continues to be a stable significant source of income for our shareholders.
And with that, I'll turn the call back over to Kevin.