The Company’s portfolio of available-for-sale securities consists of U.S. Treasuries and high credit quality corporate debt securities. The following is a summary of the Company’s available-for-sale securities at September 30, 2020 and December 31, 2019:

	September 30, 2020
			Gross		Gross		Fair Value
	Amortized		Unrealized		Unrealized		(Net Carrying
	Cost		Gains		Losses		Amount)

U.S. Treasury securities	$	3,234,037	$	4,051	$	—	$	3,238,088
Corporate debt securities		8,394,072		—		—		8,394,072
Total available-for-sale securities	$	11,628,109	$	4,051	$	—	$	11,632,160

	December 31, 2019
			Gross		Gross			Fair Value
	Amortized		Unrealized		Unrealized			(Net Carrying
	Cost		Gains		Losses			Amount)
U.S. Treasury securities	$	5,962,224	$	394	$	(635	)	$	5,961,983
Corporate debt securities		19,448,239		—		—			19,448,239
Total available-for-sale securities	$	25,410,463	$	394	$	(635	)	$	25,410,222

There were no gross unrealized losses relating to the Company’s available-for-sale securities investments as of September 30, 2020. The net adjustment to unrealized holding gains (losses) on available-for-sale securities, net of tax in other comprehensive income totaled $(17,501) and $4,060 for the three and nine months ended September 30, 2020, respectively and ($1,864) and $2,308 for the three and nine months ended September 30, 2019, respectively.

Contractual maturities of debt investment securities at September 30, 2020 are shown below. Expected maturities will differ from contractual maturities because the issuers of the securities may have the right to prepay obligations without prepayment penalties.

	Under
	1 Year		1 to 2 Years		Total
U.S. Treasury securities	$	3,238,088	$	—	$	3,238,088
Corporate debt securities		8,394,072		—		8,394,072
Total available-for-sale securities	$	11,632,160	$	—	$	11,632,160

For debt securities, the Company determines whether it intends to sell or if it is more likely than not that it will be required to sell impaired securities. This determination considers current and forecasted liquidity requirements, regulatory and capital requirements and securities portfolio management. For all impaired debt securities for which there was no intent or expected requirement to sell, the evaluation considers all available evidence to assess whether it is likely the amortized cost value will be recovered. The Company conducts a regular assessment of its debt securities with unrealized losses to determine whether securities have other-than-temporary impairment considering, among other factors, the nature of the securities, credit rating or financial condition of the issuer, the extent and duration of the unrealized loss, expected cash flows of underlying collateral, market conditions and whether the Company intends to sell or it is more likely than not that the Company will be required to sell the debt securities. As the Company did not have any unrealized losses as of September 30, 2020, there were no other-than-temporary impairments of its available-for-sale securities.