Michael J. Sewell
Chief Financial Officer, Senior Vice President and Treasurer (Principal Accounting Officer) at Cincinnati Financial
Thank you, Steve, and thanks for all of you joining us today. Our investment portfolio continued to perform very well during the second quarter of 2021, including investment income growth of 5%. Dividend income was up 13% for the second quarter compared with the same quarter a year ago. For the first half of the year, net purchases for the equity portfolio totaled $42 million. Interest income from our bond portfolio grew 3% and the pretax average yield was 4.02%, down nine basis points from the second quarter a year ago. The yield on a six month basis matched last years first half. The average pretax yield for the total of purchased taxable and tax-exempt bonds during the second quarter of 2021 was 3.33%. Investing in the fixed maturity portfolio continues to be a priority, with net purchases during the first six months of the year totaling $465 million. Investment portfolio valuation changes for the second quarter of 2021 were favorable for both our stock portfolio and our bond portfolio. The overall net gain was $652 million before tax effects, including $489 million for our equity portfolio and $141 million for our bond portfolio. At the end of the second quarter, total investment portfolio net appreciated value was approximately $6.9 billion, including $5.9 billion in our equity portfolio. We had another quarter of strong cash flow, again, contributing to investment income. Cash flow from operating activities for the first six months of 2021 generated $917 million, up 49% from a year ago. Expense management is always an important matter as we work to achieve a good balance between strategic business investments and expense controls.
The second quarter of 2021 property casualty underwriting expense ratio was 0.6 percentage points lower than last years second quarter which included a stay-at-home policyholder credit for personal auto policies and higher credit losses due to uncollectible premiums. The second quarter ratio was higher than the first quarter of this year, largely due to higher accruals related to profit sharing in the second quarter and lower expenses in the first quarter that benefited from less business travel. Next, Ill highlight a few items regarding loss reserves and reinsurance. Our approach to reserving remains consistent and aims for net amounts in the upper half of the actuarially estimated range of net loss and loss expense reserves. During the second quarter of 2021, we experienced $119 million of property casualty net favorable development on prior accident years. The combined ratio effect was 7.8% for the quarter. As we do each quarter, we consider new information such as paid losses and estimate ultimate losses and loss expenses by accident year and line of business. Based on our study of new data during the year, we update estimates as needed. Together, our workers compensation and commercial casualty lines of business represent about half of our $7 billion quarter-end total gross property casualty loss and loss expense reserves and they had the largest amounts of second quarter favorable net reserve development. Workers compensation has the longest tail as claims can remain open for many years. While the amount of reserve release for any given accident year was relatively small, the aggregate amount was $27 million. Commercial casualty paid loss development by accident year over time is an important factor in estimating ultimate losses. Calendar year basis data is not as useful. For example, while the second quarter 2021 paid loss total for commercial casualty was higher than a year ago, for the first six months of 2021, it was 15% less than what we saw prior to the pandemic in the first half of 2019 despite earned premiums that were 13% higher in 2021.
Net favorable reserve development during the second quarter was concentrated in the four most recent accident years, including a little more than 2/3 for accident years 2017 through 2019. On an all-lines basis by accident year, net reserve development for the first half of the year was favorable by $170 million for 2020, $26 million for 2019, $15 million for 2018 and $18 million in aggregate for accident years prior to 2018. Nearly 80% of the 2020 amount was for property or auto lines of business, which have a much shorter tail than workers compensation or commercial casualty. Regarding reinsurance, we disclosed in our 10-Q that we nonrenewed our combined property catastrophe occurrence excess of loss treaty that provided up to $50 million of coverage for business written on a direct basis and by Cincinnati Re. And we restructured the reinsurance program in place for Cincinnati Re only that provides property catastrophe excess of loss coverage now with a total available aggregate limit of $48 million. Another reinsurance detail we disclosed pertain to cyber insurance that we offer as an affirmative coverage option on various policies. Some recent industry reports indicate that on a direct written basis -- premium basis, Cincinnati insurance is among the 20 largest cyber insurers in the U.S. Premiums for those policies are ceded to a reinsurer, therefore transferring substantially all of that risk. Ill briefly comment on capital management. Our approach remains consistent, and we ended the quarter with outstanding financial strength and financial flexibility. In typical fashion, Ill wrap up my prepared remarks [Technical Issues] of our value-creation ratio.
Property casualty underwriting increased book value by $1.08. Life insurance operations increased book value $0.07. Investment income other than life insurance and net of noninsurance items added $0.80. Net investment gains and losses for the fixed income portfolio increased book value per share by $0.69. Net investment gains and losses for the equity portfolio increased book value by $2.40. And we declared $0.63 per share in dividends to shareholders. The net effect was a book value increase of $4.41 per share during the second quarter to a record high $73.57 per share.
And now Ill turn the call back over to Steve.