We transact business primarily through our seventeen insurance subsidiaries domiciled in the United States and five insurance subsidiaries domiciled internationally, primarily in Europe. We are authorized to write business in all 50 states in the United States and in the European Union. Through our subsidiary, AmTrust at Lloyd's, we are licensed to underwrite business internationally in locations where Lloyd's is licensed. Our principal operating subsidiaries are rated "A" (Excellent) by A.M. Best Company ("A.M. Best").
On January 6, 2015, we acquired TMI Solutions, LLC ("TMIS") for approximately $29.5 million in cash and a contingent earn-out provision valued at $32.0 million. TMIS offers monthly billed warranty solutions for a variety of consumer electronics as well as consumer protection services. TMIS's warranties are primarily distributed in conjunction with large telecommunication monthly customer billing services and their customers include various Fortune 500 companies. As a result of the acquisition, we obtained certain identifiable intangible assets of approximately $32.5 million and recorded goodwill of approximately $38.3 million. The goodwill and intangible assets, as well as TMIS's results of operations, are included as a component of the Specialty Risk and Extended Warranty segment. As a result of this acquisition, we recorded approximately $13.7 million of service and fee income related to TMIS during the year ended December 31, 2015.
Gain (loss) on Investment in Life Settlement Contracts. The gain (loss) on investment in life settlement contracts includes the gain (loss) on acquisition of life settlement contracts, the gain (loss) realized upon a mortality event and the change in fair value of the investments in life settlements as evaluated at the end of each reporting period. We determine fair value based upon our estimate of the discounted cash flow related to policies (net of the reserves for improvements in mortality, the possibility that the high net worth individuals represented in our portfolio may have access to better health care, the volatility inherent in determining the life expectancy of insureds with significant reported health impairments, the possibility that the issuer of the policy or a third party will contest the payment of the death benefit payable to us and the future expenses related to the administration of the portfolio), which incorporates current life expectancy assumptions, premium payments, the credit exposure to the insurance company that issued the life settlement contracts and the rate of return that a buyer would require on the policies as no comparable market pricing is available. The gain (loss) realized upon a mortality event is the difference between the death benefit received and the recorded fair value of that particular policy. We allocate gain (loss) on investment in life settlement contracts to our segments based on gross written premium by segment.
Notwithstanding the inherent uncertainty, we have not observed material variability in our loss development factors for our largest books of business. We believe that it is reasonably likely that we could experience a 5% deviation in our loss and loss adjustment expense reserves due to changes in the elements that underlie loss development, such as claims frequency or severity.
Other Investments. Other investments consisted primarily of investments in private limited partnerships, real estate partnerships and annuities. Other investments accounted for approximately 1.4% of our investment portfolio as of December 31, 2015, which we believe is immaterial to our overall financial position or results of operations. We use the equity method of accounting to account for a majority of our other investments, which are typically accounted for on a three month lag basis. For the other investments reported at fair value, we estimate the fair value based on significant unobservable inputs in the valuation process. As a result, we classified the fair value estimates as Level 3 in the financial hierarchy.
Service and Fee Income. Service and fee income increased $68.5 million, or 16.7%, to $478.2 million from $409.7 million for the years ended December 31, 2015 and 2014, respectively. We increased service and fee income by approximately $46.2 million from acquisitions, including Oryx, TMI and Warranty Solutions. Additionally, fees for services provided to Maiden, NGHC and ACP Re increased by approximately $17.8 million in 2015 compared to 2014.
Income Before Other Income (Expense), Income Taxes and Equity in Earnings of Unconsolidated Subsidiaries. Income before other income (expense), income taxes and equity in earnings of unconsolidated subsidiaries increased $87.4 million, or 19.5%, to $535.9 million from $448.4 million for the years ended December 31, 2015 and 2014, respectively. The change in income from 2015 to 2014 resulted primarily from an increase in underwriting income of approximately $33 million, an increase of income from our fee based business of approximately $38 million and an increase in income from our investment portfolio of approximately $16 million.
Net Investment Income. Net investment income increased $46.8 million , or 55.2%, to $131.6 million from $84.8 million for the years ended December 31, 2014 and 2013, respectively. The increase resulted primarily from having a higher average portfolio of fixed security investment securities during 2014 compared to 2013, as a result of the acquisitions of AmTrust at Lloyd's, Insco Dico and Comp Options, the issuance of preferred stock and cash generated from operations, partially offset by lower overall yields.
The table below summarizes the credit quality of our fixed maturity securities as of December 31, 2015 and 2014, as rated by Standard and Poor’s.
proportional programs. In addition, certain of our reinsurance treaties allow us to share in any net profits generated under such treaties with the reinsurers. Various reinsurance brokers may arrange for the placement of this reinsurance coverage on our behalf and are compensated, directly or indirectly, by the reinsurers. We also place reinsurance with direct reinsurance markets and enter reinsurance relationships with third-party captives formed by agents and other business partners as a mechanism for sharing risk and profit. In order to reduce our exposure to reinsurance credit risk, we evaluate the financial condition of our reinsurers and place our reinsurance with a diverse group of companies and syndicates that we believe to be financially sound. We carefully monitor the credit quality of our reinsurers when we place new and renewal reinsurance, as well as on an ongoing, current basis. We use objective criteria to select and retain our reinsurers, including requiring minimum surplus of $500 million and a financial strength rating of “A-” or better from A.M. Best or Standard & Poor's Corporation. We approve exceptions to these criteria when warranted.