We do not believe that the over-capitalization of the market is uniform across all industry participants and there are many insurers and reinsurers with lower financial security profiles than ours that have and will continue to suffer disproportionately. We believe the value proposition of our reinsurance offering and our differentiated underwriting strategy positions us well to compete for new, targeted business in niche areas that we know and service well.
For the year ended December 31, 2014, our ceded premiums increased by $10.7 million partially relating to a retrocession contract purchased during 2014 in order to reduce our net exposure to natural peril catastrophe events, and partially relating to higher premiums on the inward contracts which were proportionally retroceded to entities affiliated with the ceding insurers.
Our total general and administrative expenses for the years ended December 31, 2015, 2014 and 2013, were $23.4 million, $24.5 million, and $21.0 million, respectively. General and administrative expenses for the years ended December 31, 2015, 2014 and 2013 included $4.3 million, $4.0 million and $3.8 million, respectively, for the expensing of the fair value of stock options, RSUs and restricted stock granted to employees and directors.
We expect our investment income, including realized and unrealized gains (or losses), to fluctuate from period to period. Fluctuations in realized and unrealized gains (or losses) are a function of both the market performance of the securities held in our investment portfolio, and the timing of additions to and dispositions of securities in our investment portfolio. Our investment advisor uses its discretion over when to realize a gain (or loss) on a particular investment. We believe that net investment income, which includes both realized and unrealized gains (or losses), is the best way to assess our investment performance, rather than analyzing the realized gains (or losses) and unrealized gains (or losses) separately.
From time to time, we incur indebtedness to our prime brokers to implement our investment strategy in accordance with our investment guidelines. As of December 31, 2015, we had borrowed $95.0 million (2014: $76.1 million) from our prime brokers for investing activities and to provide collateral for unrealized losses on short positions. In accordance with Greenlight Re's investment guidelines, DME Advisors is allowed to use up to 15% (GRIL: 5%) net margin leverage for extended periods of time and up to 30% (GRIL: 20%) net margin leverage for periods of less than 30 days.
Additionally, as of December 31, 2015, we had borrowed $301.4 million (2014: $135.0 million) under term margin agreements from prime brokers to provide collateral for trust accounts and for some of our letters of credit outstanding, whereby we pledge certain investment securities to borrow cash from the prime brokers.
Although GLRE is not subject to any significant legal prohibitions on the payment of dividends, Greenlight Re and GRIL are each subject to regulatory minimum capital requirements and regulatory constraints that affect their ability to pay dividends to us. In addition, any dividend payment would have to be approved by the relevant regulatory authorities prior to payment. As of December 31, 2015, Greenlight Re and GRIL both exceeded the regulatory minimum capital requirements. See Note 9 of the consolidated financial statements for details of statutory surplus and regulatory capital of Greenlight Re and GRIL.