Chairman, Chief Executive Officer at Travelers Companies
Thank you, Abbe, good morning, everyone, and thank you for joining us today. We are very pleased to report exceptional top and bottom-line results for the quarter. Core income earnings per share and return-on-equity, were all record highs, driven by both underwriting and investment results. Our underwriting gains were broad-based in each of our three segments underlying underwriting income was higher and prior year development was favorable.
Catastrophe losses were also light. Record underlying -- underwriting income, resulting from net earned premiums of $10 billion, up more than 13%[phonetic] over the prior year quarter and an underlying combined ratio, which improved 5.5 points to a record 85.9%. Looking at our two commercial segments together. The aggregate BI/BSI underlying combined ratio was an excellent 85.9% for the quarter. The underlying combined ratio in personal insurance was coincidentally also 85.9%, an improvement of more than 10 points Year-over-Year. In addition, we are pleased to have delivered full-year core income of $3.1 billion, generating core return-on-equity of 11.5%. Notwithstanding elevated industry-wide catastrophe losses earlier in the year and a personal lines operating environment that while improving was difficult during the year.
Turning to investments, our high-quality investment portfolio continued to perform well, generating after tax net investment income of $645 million, for the quarter and $2.4 billion for the year driven by strong and reliable returns from our growing fixed-income portfolio. Our operating results together with our strong balance sheet enabled us to grow adjusted book-value per share by 8% during the year after making important investments in our business and returning nearly $2 billion of excess capital to shareholders through dividends and share repurchases. Turning to the topline, we grew net written premiums by 13% to $10 billion in the quarter. For the year, we grew net written premiums by 14% to more than $40 billion.
All three segments contributed to our topline success. In business insurance, we grew net written premiums in the quarter by 14% to more than $5 billion. Renewal premium change remained high at 11.8%, our retention also remained high at 87%. The combination of strong pricing and retention reflects deliberate execution on our part and a disciplined marketplace. This segment generated $672 million of new business in the quarter which is a $118 million or about 20% higher than in the prior year quarter. In Bond and Specialty Insurance net written premiums increased by 7% to $989 million driven by excellent production in our surety business where net written premiums were up 9%.
Production was also strong in our management liability business. Given the attractive returns we are very pleased with the strong production results in both of our commercial business segments. In Personal Insurance topline growth of 13% was driven by higher pricing. Renewal premium change was 21.2% in home and 16.7% in our auto business. Renewal premium change alone contributed more than $2 billion of written premium in this segment over the past year. With another strong production -- with another year of strong production in each of our segments we feel very well-positioned for the new year. You'll hear more shortly from Greg, Jeff, and Michael about our segment results.
Before I turn the call over to Dan, I'd like to take a minute and put our 2023 results into an overtime context with an update to some data we shared previously. Half-dozen or so years ago, we laid out a focused innovation strategy. I'm sure that if we were successful in its execution we would expect to grow our business at attractive returns. A reflection of our belief that any strategy to achieve industry-leading returns over time requires a strategy to grow over time. The data on slide 19 of the webcast presentation show the success we've achieved. Starting at the top-left corner in terms of the topline we've grown net written premiums at a compound annual rate of 7% over the past seven years. That's 2.5 times our rate of growth from 2012 to 2016.
The growth rate in each of the past two years was double-digits. The result of a deliberate and tailored strategy. Stronger pricing where we need it and the combination of pricing and unit growth where we like the opportunity. In Business Insurance, we've added more than $4 billion to our topline over the past two years. The investments we've made in capabilities to enhance the franchise value that we offer to our customers and distribution partners have contributed to strong retention and growth in new business. In bond and specialty, we've increased net written premiums over that period by about $0.5 billion or 14%. More than half of that growth has come from a very profitable surety business where our market-leading position has enabled us to benefit from increased demand for bonds with higher contract values and projects, resulting from the federal infrastructure, and jobs act and other federal programs.
Across both of our commercial segments since 2021, we have about doubled our E&S writings to around $2.5 billion. That includes organic growth from the E&S business we write national property, our Northfield business and our Lloyd's business. As well as the impact of more recent strategic efforts, which include our relationships with Fidelis and Corvus. The margins in our E&S business are quite attractive. In personal insurance where margins have not been at target levels in recent periods. Net written premium growth of $3.4 billion over the past two years has been almost entirely a result of price increases. The PI team has done an excellent job of threading the needle maintaining a strong customer base, while achieving meaningful pricing gains. We've also done a great job with product management.
Our advanced peril by peril Quantum Auto 2.0 offering now represents more than 60% of the domestic property portfolio and adoption of our Telematics product IntelliDrive among new customers has been strong with pricing gains and enhanced product sophistication the book should contribute to our earnings power going-forward as we move toward target returns. Also important is that across all three segments we have grown mostly in products, classes of business, and geographies and through distribution partners that we know well. That gives us a lot of confidence in the business we're adding to the book. Moving to the right you can see that while we have meaningfully increased our rate of growth we've maintained very strong and consistent underlying profitability that demonstrates that we're not growing by underpricing the business or compromising our underwriting discipline.
We've grown by investing in the products, services, and experiences that our customers want to buy and our distribution partners want to sell. We've also grown to a lot of great hustle and hard work on the part of our outstanding field organization. One of the clear strategic objectives of our innovation strategy has been to optimize productivity and efficiency. Moving to the top-right of the slide, you can see that over the last seven years, we've reduced our expense ratio by 3.6 points just over 28% for 2023 which is more than a 10% reduction relative to our 2012 to 2016 expense ratio of around 32%. Enhanced operating leverage gives us the flexibility to let the benefit fall to the bottom-line and/or invest further in our strategic priorities.
Case in point. As you can see on slide 21, since 2017, we have doubled our investments in strategic technology initiatives. Over that same-period we've carefully managed growth in routine but necessary technology expenditures. In other words, over a seven-year period we simultaneously and meaningfully increased our technology spend, improved the strategic mix of that spend, and lowered our expense ratio. The upshot of what we've accomplished on the top half of slide 19, is what you see on the bottom half. On the bottom-left, you can see that we've increased underlying underwriting income significantly. From 2012 to 2019 underlying underwriting income averaged $1.3 billion. In 2020, we crossed the $2 billion mark and 2023, marks the first time that we've exceeded $3 billion.
We've taken our underlying underwriting income to a meaningfully higher-level. We've also significantly increased our cash-flow from operations to more than $7.5 billion in 2023. The fourth consecutive year it's been more than $6 billion and more than double our average cash-flow from operations in the earlier part of the last decade. Cash flow, isn't a metric that we or industry talk a lot about, but it's important. It's what gives us the ability to make important investments in our business, return excess capital to shareholders, and grow the investment portfolio. We've grown our investment portfolio significantly to nearly $93 billion. As we continue to reinvest our fixed-income portfolio at higher rates this is a highly reliable lever of earnings and value-creation.
To sum it up through a well-executed strategy we've more than doubled our rate of growth, sustained strong underlying underwriting margins, and meaningfully lowered our expense ratio. That has resulted in record levels of underlying underwriting income, cash-flow, and invested assets. Ultimately of course one number that brings everything together is adjusted book-value per share. On slide 20, you can see that we have steadily increased adjusted book value per share each year since 2006 at a compound annual rate of 7.5%. The effective management of our capital complements that resolve[phonetic]. We've increased our capital base to support the profitable growth of our business. At the same time, we've been disciplined about returning excess capital to shareholders.
Over this period, we've increased our dividend at a compound annual rate of more than 8% and returned more than $40 billion to our shareholders through share repurchases at an average price of about $74 per share. These results together with our track record of strong returns and low-volatility demonstrate the strength of our business and the success of our overtime strategy. Looking ahead, we're very confident about how we're positioned for 2024 and beyond. The fundamentals across our business are in excellent shape. We're confident that we're focused on the right strategic priorities and that with demonstrated success and execution there's plenty more opportunity ahead of us. And with that, I'm pleased to turn the call over to Dan.