Thank you. Good morning, and welcome, everyone, to the Donegal Group conference call for the third quarter ended September 30, 2013. I'm Jeff Miller, Chief Financial Officer, and I will begin today's call by discussing highlights of our quarterly financial results. Don Nikolaus, President and Chief Executive Officer, will then provide additional commentary on the quarter and an update on our business trends.
Please be aware that certain statements made in our news release and in this conference call are forward-looking in nature and involve a number of risks and uncertainties. We refer you to our news release for more information about forward-looking statements. Further information on risk factors that could cause actual results to differ materially from those projected in the forward-looking statements is included in our 2012 Form 10-K, which is available on our website under the SEC Filings link. Reconciliation of non-GAAP information as required by SEC Regulation G, was provided in our news release, which we have also made available in the Investors section of our website.
Focusing in on the third quarter results, we are pleased to report a 12% increase in net income and a 24% increase in operating income. I will discuss a number of contributing factors to the improvement. We are particularly pleased with the underwriting results, producing a 96% statutory combined ratio for the quarter.
Earned premiums continue to grow at an 8% pace in the third quarter, underscoring the ongoing success of our growth strategies and playing a large role in our increased earnings.
We achieved net premiums written growth of 5.7% for the quarter. As in recent periods, the growth reflects premium rate increases in nearly all of our business lines, a continuation of commercial line's new business growth and additional premiums retained by Michigan Insurance Company as a result of the reinsurance change we have discussed in prior calls.
Turning to loss trends, also contributed to our underwriting profit for the quarter. Let's begin with weather losses. We incurred $9.4 million of weather-related losses during the third quarter. That's in line with our average third quarter amount for the previous 5 years. It's also below the $11.3 million weather losses reported in last year's third quarter.
We had no significant impact during the quarter from any PCS-designated catastrophe events in our operating areas, but we did incur losses from localized wind and hail storms in the Midwest, including $500,000 in losses from a hailstorm in Iowa at the end of August.
Large fire losses totaled $3.1 million for the quarter. That's well below our quarterly average over the past 2 years and down significantly from $5.7 million in the second quarter of 2013 and $6.6 million we incurred in last year's third quarter.
We saw decreases in large fire losses for both homeowners and commercial property lines of business, contributing to excellent quarterly loss ratios in those 2 business lines.
Our personal lines combined ratio of 97.9% represented significant improvement over the prior year quarter, again, benefiting from rate increase activity and underwriting actions we have taken over the past few years, as well as the lower levels of weather and large fire losses.
Our commercial lines combined ratio was an excellent 93%, and would have been even better had it not been for a few large losses in our commercial auto line of business. Those losses added about $2 million to third quarter incurred losses and explained the uptick in our commercial auto combined ratio.
You may recall, last quarter, we talked about an increase in the number of workers' compensation losses that exceeded $50,000 during that quarter. Those losses added about $4.7 million to our second quarter incurred losses. We did not see a recurrence of that activity during the third quarter, as large workers' comp losses added $3 million to our losses incurred, which was in line with the $2.8 million we incurred in the third quarter of 2012. As a result, our workers' comp combined ratio was a very favorable 93% for the third quarter, contributing to an improvement in our commercial lines loss experience compared to the first half of the year.
Prior-accident year loss reserve development added $3.1 million to total losses in the quarter, in line with the $2.9 million we experienced for the third quarter 2012. Approximately $800,000 of the current quarter reserve development was related to a single commercial auto claim from last year, for which we received new information during the quarter. We are continuing to book our reserves at the midpoint of our actuarial reserve estimates, and we view the adverse development during the quarter and first 9 months of the year to be within an acceptable range relative to our $266 million in net reserves. Those reserves represent our best estimates based on currently known facts and circumstances, and we continue to have confidence in the adequacy of our reserves.
Summarizing our underwriting results for the quarter, we're quite pleased to have achieved a 96% statutory combined ratio and a 97.6% GAAP combined ratio, which were the lowest quarterly combined ratios we have reported since the third quarter of 2008. It is worth noting that the strong profitability did lead to higher projected incentive compensation expense to our agents and employees, which put the statutory expense ratio at 30.6% versus 29.1% in last year's third quarter.
Turning to the investment portfolio. The low yield environment continues to present challenges to our efforts to maintain investment income. However, the decline in investment income slowed from the 5% pace we experienced for the first half of the year to less than 2% for the third quarter. We made the strategic decision to accumulate cash during the third quarter to position ourselves to take advantage of potential opportunities in the current volatile rate environment. We are currently considering a focus for new money investments on shorter duration fixed maturities and dividend-paying equities.
Our book value per share increased sequentially to $14.95 at September 30, 2013, from $14.84 at June 30, 2013, as a result of our net income and fluctuations in our portfolio market value. We repurchased a modest 4,240 shares of Class A common stock during the quarter at an average cost of $14.16 per share. Our Board of Directors last week approved quarterly dividends of $0.1275 per share of Class A common stock and $0.115 per share of Class B common stock, payable November 15 to stockholders of record as of November 1.
Before I turn the microphone over to Don, let me state a few facts about our stock option compensation and the effective stock options on our earnings per share and book value per share, since there has been some recent publicity that indicate some misunderstanding about that subject.
First of all, the objective of our stock option plan is to provide a long-term incentive for our management team and directors to achieve sustained financial and operational performance and to align their interest with the interest of our stockholders. Stock options have been granted to a broad group of management personnel. For example, 270 individuals received stock option grants in 2012.
Secondly, stock options have always been issued at or above the market price of our stock on the date of grant, and they provide compensation only if our stock price appreciates. Accordingly, very few stock options have been exercised over the past 5 years. In fact, the number of shares outstanding has increased by only about 700,000 shares or 3.5% from December 31, 2007 to September 30, 2013. Further, no directors or senior officers have received any compensation from option exercises in the past 5 years. In fact, over 3.2 million stock options expired in the last 4 years, without providing any compensation whatsoever, reinforcing the performance-based nature of our stock option plan.
The last point I want to make on this topic is that outstanding stock options have resulted in very little dilution to our earnings per share. For the first 9 months of 2013, our earnings per share were diluted by only $0.01 per share or 1.5% of our basic earnings per share. Also, any dilution of our book value per share from future option exercises will be limited because the average exercise price on outstanding options is very close to our current book value per share. Any new shares we issue on the exercise of options will provide additional capital that we can deploy to expand our business. Said differently, option exercises provide an infusion of capital, which limits the dilutive effect of the additional shares we issue.
In summary, we continue to believe that stock options are an effective form of performance-based compensation that is aligned with the interest of our long-term stockholders.
With that, I'll turn the call over to Don for his comments on the quarterly results.