Note 2 — Securities

The following is a summary of securities available for sale as of December 31, 2019 and 2018:

The amortized cost and estimated fair value of securities as of December 31, 2019, by contractual or expected maturity, are shown below. Collateralized mortgage obligations are included in the table shown below based on their expected maturities. All other securities are included based on their contractual maturities.

ASC 320, “Investments – Debt and Equity Securities,” requires us to periodically evaluate our investments for other-than-temporary impairment (“OTTI”). There was no OTTI charge during the year ended December 31, 2019.

Gross unrealized losses on securities available for sale, the estimated fair value of the related securities and the number of securities aggregated by investment category and length of time that individual securities have been in a continuous unrealized loss position, were as follows as of December 31, 2019 and 2018:

All individual securities that have been in a continuous unrealized loss position for 12 months or longer as of December 31, 2019 and December 31, 2018 had investment grade ratings upon purchase. The issuers of these securities have not established any cause for default on these securities and the various rating agencies have reaffirmed these securities’ long-term investment grade status as of December 31, 2019 and December 31, 2018. These securities have fluctuated in value since their purchase dates as market interest rates have fluctuated.

The Company does not intend to sell these securities and it is more likely than not that it will not be required to sell the investments before the recovery of its amortized cost basis. In addition, the unrealized losses on municipal securities are not considered other-than-temporarily impaired, as the bonds are rated investment grade and there are no credit quality concerns with the issuers. Interest payments have been made as scheduled, and management believes this will continue in the future and that the bonds will be repaid in full as scheduled. Therefore, in management’s opinion, all securities that have been in a continuous unrealized loss position for the past 12 months or longer as of December 31, 2019 and December 31, 2018 were not other-than-temporarily impaired, and therefore, no impairment charges as of December 31, 2019 and December 31, 2018 were warranted.

Realized gains and losses on sales of securities and proceeds from sales of securities were as follows for the periods indicated:

In January 2016, FASB issued ASU 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities (Topic 825). This new guidance, among other provisions, amends accounting related to the classification and measurement of investments in equity securities. We adopted this guidance, as required, in the first quarter of 2018. ASU 2016-01 requires the amounts reported in accumulated other comprehensive income for equity securities that exist as of the date of adoption previously classified as available-for-sale be reclassified to retained earnings. The Company reduced the balance of securities by $529,000 as of January 1, 2018, representing the loss related to all of our mutual fund equity securities, which resulted in a net reduction of retained earnings of $382,000 and an increase of $147,000 in net deferred tax assets based on the transition requirements of this standard.

For the year ended December 31, 2019, the Company recorded $1.3 million in net realized gain from sale of securities that had previously been recognized as net unrealized gains of $586,000 in comprehensive income. This included the sale of all of the Company’s tax-exempt municipal bond securities.

For the year ended December 31, 2018, the Company recorded $870,000 in net realized losses from sale of securities that had previously been recognized as net unrealized losses of $413,000 in comprehensive income. This included sale of all of the Company's mutual fund equity securities with gross realized losses of $957,000. The Company recorded a $428,000 net loss in earnings resulting from the sale of these securities. The remaining loss of $529,000 related to these sold securities was recorded as a transition adjustment upon adoption of ASU 2016-01 as of the beginning of the period as described in the preceding paragraph. For the year ended December 31, 2017, there was a $1.7 million net gain in earnings resulting from the sale of securities that had previously been recorded as net unrealized gains of $1.3 million in comprehensive income.

Securities available for sale with market values of $30.2 million and $29.9 million as of December 31, 2019 and 2018, respectively, were pledged to secure advances from the Federal Reserve Bank, Discount Window facility, and for other purposes as required or permitted by law.