The amortized cost and fair values of available-for-sale and held-to-maturity debt securities at December 31, 2019 and 2018 are summarized as follows:

All mortgage-backed debt securities are with government sponsored enterprises (GSEs) such as Federal National Mortgage Association, Government National Mortgage Association, Federal Home Loan Bank, and Federal Home Loan Mortgage Corporation.

At year-end 2019 and 2018, there were no holdings of debt securities of any issuer, other than the U.S. government and its agencies, in an amount greater than 10% of stockholders’ equity.

The amortized cost and fair value of debt securities as of December 31, 2019 and 2018 by contractual maturity are shown below. Actual maturities may differ from contractual maturities because the issuers may have the right to call or prepay obligations with or without call or prepayment penalties.

The following table shows the gross unrealized losses and fair value of debt securities, aggregated by category and length of time that securities have been in a continuous unrealized loss position at December 31, 2019 and 2018. In estimating other-than-temporary impairment losses, management considers, among other things, the length of time and the extent to which the fair value has been less than cost, the financial condition and near-term prospects of the issuer and the intent and ability of the Company to hold the security for a period of time sufficient to allow for any anticipated recovery in fair value. The unrealized losses shown in the following table are primarily due to increases in market rates over the yields available at the time of purchase of the underlying securities and not credit quality. Because the Company does not intend to sell these securities and it is more likely than not that the Company will not be required to sell the securities before recovery of their amortized cost basis, which may be maturity, the Company does not consider these securities to be other-than-temporarily impaired at December 31, 2019. There were no other-than-temporary impairments for the years ended December 31, 2019, 2018 and 2017.

At December 31, 2019, 35 of the Company’s 650 debt securities were in an unrealized loss position for more than 12 months.

The following table summarizes information about sales of debt securities available for sale.

The carrying value of debt securities pledged to secure public funds on deposits and for other purposes as required by law as of December 31, 2019 and 2018 was $389.9 million and $291.6 million, respectively.