The Company held no investment securities as of March 31, 2022. Investment securities as of December 31, 2021 consisted of the following:


December 31, 2021	Amortized cost		Gross unrealized gains		Gross unrealized losses			Estimated fair value
Federal agency bonds — mortgage-backed	$	8,696,093	$	—	$	(61,016	)	$	8,635,077
Total debt securities available-for-sale	$	8,696,093	$	—	$	(61,016	)	$	8,635,077

The amortized cost and estimated fair value of investment securities as of December 31, 2021, by contractual maturity, are shown below:


	Available-for-sale
December 31, 2021	Amortized cost		Estimated fair value
Due after one year through five years	$	8,696,093	$	8,635,077
Total debt securities available-for-sale	$	8,696,093	$	8,635,077

Investment securities with an estimated fair value of $8,635,077 as of December 31, 2021 were pledged to secure our revolving line of credit. See Note 6 for additional information.

The Company recorded sales of available-for-sale debt securities during the three months ended March 31, 2022 of $8,513,783 and recognized a loss on the sale of $182,310. The Company recorded no sales or maturities of available-for-sale securities during the three months ended March 31, 2021.