Amortized cost, allowance for credit losses, gross unrealized gains/losses in accumulated other comprehensive income (loss) and fair value of marketable debt securities, by type of security consisted of the following (in thousands):

 

 

The Company’s investments in marketable debt securities, that have been in a continuous unrealized loss position, for which an allowance for credit losses has not been recorded, by type of security consisted of the following (in thousands):

 

 

Gross realized gains and losses from the sales of the Company’s marketable debt securities, consisted of the following (in thousands):

 

 

The Company invests its excess cash in a diversified portfolio of fixed and variable rate debt securities to meet current and future cash flow needs. All investments are made in accordance with the Company’s approved investment policy. As of March 31, 2022, the portfolio had an average credit rating of AA and a weighted term to contractual maturity of 1.4 years, with 161 securities in the portfolio representing an unrealized aggregate loss $2.7 million or 1% of amortized cost, and a weighted average credit rating of AA+.

As of March 31, 2022, the Company performed an impairment analysis and determined an allowance for credit losses was not required. The Company determined that it did not have an intent to sell and it was not more likely than not that the Company would be required to sell any security based on its current liquidity position, or to maintain compliance with its investment policy, specifically as it relates to minimum credit ratings. The Company evaluated the securities with an unrealized loss considering severity of loss, credit ratings, specific credit events during the period since acquisition, overall likelihood of default, market sector, potential impact from the current economic environment, geopolitical unrest and a review of an issuer’s and securities’ liquidity and financial strength, as needed. The Company concluded that it would receive all scheduled interest and principal payments. The Company, therefore, determined qualitatively that the unrealized loss was related to changes in interest rates and other market factors and therefore no allowance for credit losses was required.

Amortized cost and fair value of marketable debt securities, by contractual maturity consisted of the following (in thousands, except weighted average data):

 

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