Dale Thatcher
Analyst · RBC Capital Markets
Good morning. In an otherwise difficult year, we're pleased with our fourth quarter results. We took advantage of the positive pricing momentum exhibited in the market and achieved our 11th consecutive quarter of positive commercial lines price.
Two key points to remember about our pricing strategy are, one, its consistency; and two, we're earning commercial lines rate above last trend. Also in the fourth quarter, we closed on the Montpelier E&S acquisition, rounding out our new E&S platform.
Industry-wide, 2011 was a record catastrophe year with a heavy East Coast impact from which we were not immune. This was a second consecutive record catastrophe year for us, but cat losses in the fourth quarter were in line with our expectations at approximately 2 points.
For 2011 in total, cat losses were almost $119 million or 8.3 points on a combined ratio. For the quarter, we reported operating income per diluted share of $0.33 compared to $0.48 a year ago. Favorable prior-year reserve development contributed the results, partially offset by lower net investment income and higher expenses due to the MUSIC acquisition.
The fourth quarter statutory combined ratio was 98.7%, 4 points better than a year ago. Favorable prior-year casualty reserve development of $10 million or 2.7 points, an improvement in year-on-year non-catastrophe property results drove the results. Total statutory premiums were up 17% in the quarter, driven by 20% commercial lines net premium written increase, our third sequential quarter of growth.
Commercial lines growth included E&S business, which contributed $15.7 million in the quarter, along with audit and endorsement premium of $11 million in the quarter. Audit and endorsements have now been positive for 3 quarters.
2011 marked the first year of overall net premium written growth for Selective since 2007 with a 7% increase. For the full year 2011, audit and endorsement premium added $14.5 million to commercial lines growth versus returned premium of $47.9 million in 2010. The commercial line statutory combined ratio was 98.2% in the quarter. Commercial property and commercial auto continue to perform well in the quarter, reporting combined ratios of 75% and 96.3% respectively.
Workers compensation result showed further improvement in the quarter with a statutory combined ratio of 111.9% versus 123.8% a year ago. Again this quarter, workers compensation results had no prior year development. We continue to address profitability in this line through a combination of rate increases, underwriting improvements and claims initiatives.
The BOP line reported fourth quarter statutory combined ratio of 80.7%, including $4 million or 22.5 points of favorable prior-year casualty development. In our standard quarterly reserve review, we determine the BOP reserves to be developing a redundancy that required action. Recent actuary year combined ratios have been running in the 110% to 115% range, which includes the more normalized catastrophe load and is more representative of current results in this line.
Personal line statutory net premiums written were up 6% in the quarter and the statutory combined ratio was 101.5%. We achieved renewal rate increases of 6.1%, while underlying results showed improvement in the quarter, there are still not where they need to be.
To improve personalized profitability, we continue to focus on driving rate and mix of business changes across our personal lines book. We successfully renewed the property catastrophe reinsurance in January. The program structure remains $435 million in excess of $40 million retention.
Pricing was up consistent with exposure change in recent market trends due to increased global catastrophe losses and reinsurers focus on RMS 11. The result was a $3.5 million increase from 2011 in seeded premium to $22 million. The diversification of the program remains strong and is comprised of a group of financially solid reinsurers with an average-A rating from A. M. Best.
Fourth quarter after-tax net investment income declined 27% from a year ago to $22.6 million. This decline was largely driven by alternative investments which produced a $3 million pre-tax loss versus income of $9 million in the 2010 fourth quarter.
For the year overall, our alternative investment portfolio generated a 17% return or $21 million in income primarily from increased distribution. The after-tax yield on fixed maturity securities was 2.8%, flat with last quarter, but down from 2010 levels. Lower reinvestments rates will place ongoing pressure on the total yield generated on our fixed income portfolio.
We maintained a well laddered investment portfolio, but as bonds mature and reinvest at current depressed market rates, we expect the yield on our portfolio to remain under pressure. Invested assets increased 5% from a year ago to $4.1 billion. Our fixed income portfolio has an overall credit rating of AA-minus and the duration of 3.1 years including short term investments. After suspending purchases of municipal securities in 2011, we're now selectively buying high quality municipal bonds for the portfolio which will slightly extends duration.
We continue to invest primarily in high quality corporate bonds while maintaining an overall duration of just over 3 years. The only Eurozone sovereign debt exposure in the portfolio is to Germany and Finland, and it totals less than $13 million. Our total exposure to the Eurozone is $63.9 million which includes $30.9 million in bank fixed income, $19.4 million in corporate fixed income and $1.1 million in equity exposure to one Eurozone consulting firm.
All of our securities are monitored closely and we are comfortable with the minimal exposure we have at the present time. The increase in our short term investment position in the quarter was due largely to the assets acquired with the MUSIC transaction.
In the fourth quarter, we reduced our held-to-maturity fixed income portfolio by approximately $100 million due to changes in the credit quality on certain securities as a result of rating downgrade that took AA rated securities to AA-.
We had an unrealized gain position of $150 million pre-tax at the December 31, 2011 up from $83 million a year ago. The unrecognized gain position in the fixed income held-to-maturity portfolio was $46 million pre-tax or $0.55 per share after-tax.
As previously disclosed, the deferred acquisition cost or DAC accounting change went into effect on January 1, 2012. This was a onetime $51 million after-tax adjustment to stockholders equity and the corresponding $1 decrease in book value per share. Book value as of March 31, 2012 will reflect this change.
On Page 8, of the investor packet we have provided an exhibit detailing the impact of a DAC accounting change on our balance sheet and income statement including retroactive application of a change for prior periods. We completed our acquisition of MUSIC on December 31, which rounded out the earlier E&S renewal rights transaction with Alterra.
The structure of these transactions allowed us to remove the uncertainty around prior reserves and development by not taking the liabilities of the business and allowing us to select business based on our underwriting guidelines on a go-forward basis. As a result, no unearned premium was transferred culminating in a significant difference between written and earned premium this year. This will put modest pressure on our overall GAAP expense ratio in the first year, especially under the new DAC rules.
Surplus remains strong at $1.1 billion at December 31, while stockholders equity increased 3.6% from a year ago to $1.1 billion. Book value per share increased to $20.39 from $19.95 a year ago, partially offset by an $11 million pension plan charge as a result of lower discount rate assumptions. Our premium to surplus ratio was 1.4 to 1 at year end. And rule of share repurchase activity we deployed access capital in 2011 on the strategic acquisitions of our E&S platform to build long term shareholder value.
Now I will turn the call over to John Marchioni to review insurance operations.