Other assets decreased $26.0 million primarily due to a $5.1 million write-off of intangible assets and a $14.0 million decrease in net tax assets. The decrease in net tax assets is primarily the result of $27.2 million of deferred taxes on net unrealized gains on investment securities allocated to stockholders’ equity arising during the year ended December 31, 2009 partially offset by $12.4 million of tax benefits recorded in connection with the other-than-temporary impairment loss on our investment in AMIC.
At December 31, 2009, the Company had $27,800,000 invested in whole loan CMOs backed by Alt-A mortgages. Of this amount, 39.9% were in CMOs that originated in 2005 or earlier and 60.1% were in CMOs that originated in 2006. The Company’s mortgage security portfolio has no direct exposure to sub-prime mortgages. The unrealized losses for the equity securities was primarily due to wider spreads from preferred stocks issued by financial institutions following the disruption in credit markets since the time of their acquisition. Some of these financial institutions have exposure to sub-prime mortgages.
Approximately 10.1% of fixed maturities, primarily municipal obligations, in our investment portfolio is insured by financial guaranty insurance companies. The purpose of this insurance is to increase the credit quality of the fixed maturities and their credit ratings. If the obligations of these financial guarantors ceased to be valuable, either through a credit rating downgrade or default, these debt securities would likely receive lower credit ratings by the rating agencies that would reflect the creditworthiness of the various obligors as if the fixed maturities were uninsured. The following table summarizes the credit quality of our fixed maturity portfolio as rated, and as rated if the fixed maturities were uninsured, at December 31, 2009:
The unrealized losses on all available-for-sale securities have been evaluated in accordance with the Company's impairment policy and were determined to be temporary in nature at December 31, 2009. In 2009, the Company experienced a decrease in net unrealized losses of $87.5 million which, net of deferred taxes of $27.2 million, net of deferred policy acquisition costs of $11.5 million, and net of the net cumulative effect adjustment of $1.6 million for the adoption of recent investment accounting pronouncements, increased stockholders' equity by $47.2 million (reflecting net unrealized losses of $7.1 million at December 31, 2009 compared to net unrealized losses of $54.3 million at December 31, 2008). From time to time, as warranted, the Company may employ investment strategies to mitigate interest rate and other market exposures. Further deterioration in credit quality of the companies backing the securities, further deterioration in the condition of the financial services industry, a continuation of the current imbalances in liquidity that exist in the marketplace, a continuation or worsening of the current economic recession, or additional declines in real estate values may further affect the fair value of these securities and increase the potential that certain unrealized losses be designated as other-than-temporary in future periods and the Company may incur additional write-downs.
The chart below reflects the maturity distribution of IHC’s contractual obligations at December 31, 2009 (in thousands):
We believe the economic environment during 2008 and 2009 also created opportunities for us since many insurance companies experienced reductions in capital and surplus, while we achieved all-time highs in statutory capital and surplus. Our book value per share increased to $13.16 at December 31, 2009 from $10.56 at December 31, 2008 principally due to positive changes in the fair value of our investment portfolio. For 2010, we will emphasize: