The amortized cost and fair values of the Company's investment in securities follow:

The Company's mortgage-backed securities and collateralized mortgage obligations issued by government sponsored enterprises are guaranteed by one of the following government sponsored enterprises: Fannie Mae, Freddie Mac or Ginnie Mae.  At December 31, 2013, $988,000 of the Company's government sponsored enterprise bonds and $99.7 million of the Company's mortgage related securities were pledged as collateral to secure repurchase agreement obligations of the Company.  As of December 31, 2013, $1.2 million of municipal securities were pledged as collateral to secure Federal Home Loan Bank advances.

The amortized cost and fair value of securities at December 31, 2013, by contractual maturity, are shown below. Expected maturities may differ from contractual maturities because issuers or borrowers may have the right to prepay obligations with or without prepayment penalties.

Total proceeds and gross gains and losses from sales of investment securities available for sale for each of periods listed below.

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

The Company reviews the investment securities portfolio on a quarterly basis to monitor its exposure to other-than-temporary impairment.  In evaluating whether a security's decline in market value is other-than-temporary, management considers the length of time and extent to which the fair value has been less than cost, financial condition of the issuer and the underlying obligors, quality of credit enhancements, volatility of the fair value of the security, the expected recovery period of the security and ratings agency evaluations.  In addition the Company may also evaluate payment structure, whether there are defaulted payments or expected defaults, prepayment speeds and the value of any underlying collateral.  For certain securities in unrealized loss positions, the Company prepares cash flow analyses to compare the present value of cash flows expected to be collected from the security with the amortized cost basis of the security.

As of December 31, 2013, the Company identified two municipal securities that were deemed to be other-than-temporarily impaired.  Both securities were issued by a tax incremental district in a municipality located in Wisconsin.  During the year ended December 31, 2012, the Company received audited financial statements with respect to the municipal issuer that called into question the ability of the underlying taxing district that issued the securities to operate as a going concern.  During the year ended December 31, 2012, the Company's analysis of these securities resulted in $100,000 in credit losses that were charged to earnings with respect to these two municipal securities.  As of December 31, 2013, these securities had a combined amortized cost of $189,000 and a combined estimated fair value of $215,000.  

As of December 31, 2013, the Company had sixteen municipal securities and two mortgage-backed securities which had been in an unrealized loss position for twelve months or longer.  These securities were determined not to be other-than-temporarily impaired as of December 31, 2013.  The Company has determined that the decline in fair value of these  securities is not attributable to credit deterioration, and as the Company does not intend to sell nor is it more likely than not that it will be required to sell these securities before recovery of the amortized cost basis, these securities are not considered other-than-temporarily impaired.

Continued deterioration of general economic market conditions could result in the recognition of future other than temporary impairment losses within the investment portfolio and such amounts could be material to our consolidated financial statements.

During the year ended December 31, 2012, two private-label collateralized mortgage obligations, that had been identified as other than temporarily impaired, were sold at a combined gain of $282,000.  At the time of sale, these securities had a combined amortized cost of $18.0 million.

The following table presents the change in other-than-temporary credit related impairment charges on collateralized mortgage obligations and municipal securities for which a portion of the other-than-temporary impairments related to other factors was recognized in other comprehensive loss.