4.    Investments in Marketable Securities

Amortized cost and fair value of marketable securities, available-for-sale, by type of security consisted of the following (in thousands):

As of March 31, 2015, the amortized cost and fair value of the Company’s investment in available-for-sale securities that have been in a continuous unrealized loss position for less than 12 months were $727,000 and $715,000, respectively. As of December 31, 2014, the amortized cost and fair value of the Company’s investment in available-for-sale securities that have been in a continuous unrealized loss position for less than 12 months were $5.4 million. Unrealized losses related to these investments are due to interest rate fluctuations as opposed to changes in credit quality. In addition, the Company does not intend to sell and it is not more-likely-than-not that the Company would be required to sell these investments before recovery of their amortized cost basis, which may be at maturity. As of March 31, 2015 and December 31, 2014, the Company did not have any investments in a continuous unrealized loss position for 12 months or longer.

For the three months ended March 31, 2015, gross realized gains and gross realized losses from the sales of the Company’s available-for-sale securities were $77,000 and $3,000, respectively and were recorded in other income (expense), net in the condensed consolidated statements of net and comprehensive income.

The Company regularly reviews its investment portfolio to determine if any security is other-than-temporarily impaired, which would require the Company to record an impairment charge in the period any such determination is made. In making this judgment, the Company evaluates, among other items, the duration and extent to which the fair market value of a security is less than its amortized cost and the Company’s intent and ability to sell, or whether the Company will more likely than not be required to sell, the security before recovery of its amortized cost basis. The Company has evaluated its investments in marketable securities as of March 31, 2015 and has determined that no investments with unrealized losses are other-than-temporarily impaired.

Amortized cost and fair value of marketable securities, available-for-sale, by contractual maturity consisted of the following (dollars in thousands):

Actual maturities may differ from contractual maturities because certain borrowers may have the right to call or prepay certain obligations with or without call or prepayment penalties.