Net investment income of $87 million for the quarter represented a $16 million decrease from the fourth quarter of 2011 and a $17 million decrease from the third quarter of 2012, with the variances primarily driven by the market value of our alternative investments ("other investments"). These investments generated $15 million of income in the fourth quarter of 2012, compared to income of $25 million and $34 million, respectively, in the fourth quarter of 2011 and the third quarter of 2012.
For the full year, net investment income increased by $19 million, or 5%, in 2012. A $56 million increase in income from our other investments more than offset a $33 million reduction from fixed maturities due to lower reinvestment yields, notwithstanding higher investment balances.
Net realized investment gains for the quarter were $32 million, compared to $51 million in the prior quarter and $4 million of net realized investment losses in the prior year quarter.Capitalization / Shareholders’ Equity Our total capital at December 31, 2012 was $6.8 billion, including $1.0 billion of long-term debt and $0.5 billion of preferred equity, as compared to $6.4 billion at December 31, 2011. Diluted book value per common share, calculated on a treasury stock basis, declined by 1% to $42.97 in the fourth quarter, driven by the impact of Storm Sandy. On a year-to-date basis, diluted book value per common share increased by $4.89, or 13%, driven by operating income, valuation improvements for our available-for-sale investment portfolio and, to a lesser extent, share repurchases. On December 17, 2012, our Board of Directors authorized a new $750 million share common share repurchase plan, which replaced our existing plan set to expire at the end of 2012. As of February 4, 2013 we had $750 million of remaining authorization for common share repurchases through December 31, 2014.