⁽¹⁾ Includes Federal Home Loan Bank and Federal Reserve Bank stock, recorded at cost of $3.1 million, $4.8 million, respectively, at March 31, 2018 and includes Federal Home Loan Bank, Federal Reserve Bank and FNBB Inc. stock recorded at cost of $3.1 million, $4.8 million, and $0.8 million, respectively, at December 31, 2017.

Securities with an amortized cost of $328.3 million and $328.1 million at March 31, 2018 and December 31, 2017, respectively, were pledged to secure public deposits and for other purposes.

The Bank, as a member of the Federal Home Loan Bank of Atlanta (“FHLB”), is required to own capital stock in the FHLB based generally upon the balances of residential and commercial real estate loans, and FHLB advances.  FHLB stock which is included in equity securities is pledged to secure FHLB advances.  No ready market exists for this stock, and it has no quoted market value; however, redemption of this stock has historically been at par value.

As a member of the Federal Reserve Bank of Atlanta, the Bank is required to maintain stock in the Federal Reserve Bank of Atlanta based on a specified ratio relative to the Bank’s capital. Federal Reserve Bank stock is carried at cost.

Maturity Distribution. At March 31, 2018, the Company's investment securities had the following maturity distribution based on contractual maturity. Expected maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations. Mortgage-backed securities and certain amortizing U.S. government agency securities are shown separately because they are not due at a certain maturity date.

Unrealized Losses on Investment Securities. The following table summarizes the investment securities with unrealized losses aggregated by major security type and length of time in a continuous unrealized loss position:

Management evaluates securities for other than temporary impairment at least quarterly, and more frequently when economic or market concerns warrant such evaluation. Declines in the fair value of available-for-sale (“AFS”) and held-to-maturity (“HTM”) securities below their cost that are deemed to be other than temporary are reflected in earnings as realized losses. In estimating other-than-temporary impairment losses, the Company considers, (i) whether it has decided to sell the security, (ii) whether it is more likely than not that the Company will have to sell the security before its market value recovers, and (iii) whether the present value of expected cash flows is sufficient to recover the entire amortized cost basis. When assessing a security’s expected cash flows, the Company considers, among other things, (i) the length of time and the extent to which the fair value has been less than cost and (ii) the financial condition and near-term prospects of the issuer. In analyzing an issuer’s financial condition, management considers whether the securities are issued by the federal government or its agencies, whether downgrades by rating agencies have occurred, regulatory issues, and analysts’ reports.

At March 31, 2018, there were 538 positions (combined AFS and HTM) with unrealized losses totaling $7.8 million. 63 of these positions were U.S. government treasury securities guaranteed by the U.S. government. 236 of these positions were U.S. government agency and mortgage-backed securities issued by U.S. government sponsored entities, with the remaining 239 positions being municipal securities. Because the declines in the market value of these securities are attributable to changes in interest rates and not credit quality and because the Company has the present ability and intent to hold these investments until there is a recovery in fair value, which may be at maturity, the Company does not consider these investments to be other-than-temporarily impaired at March 31, 2018.