CASH AND CASH EQUIVALENTS AND MARKETABLE SECURITIES

The Company considers all highly liquid, short-term debt instruments with original maturities of three months or less to be cash equivalents.

Marketable debt securities consist primarily of commercial paper, medium-term corporate notes, and U.S. government and agency backed securities. The Company classifies these marketable debt securities as available-for-sale at fair value in “Marketable debt securities, at fair value.” The Company records the amortization of premium and accretion of discounts on marketable debt securities in the results of operations.

The Company uses the specific identification method as a basis for determining cost and calculating realized gains and losses with respect to marketable debt securities. The gross gains and losses realized related to sales and maturities of marketable debt securities were not material during the three and nine months ended September 29, 2018 and the fiscal year ended December 30, 2017.

Investments in available-for-sale marketable debt securities were as follows at September 29, 2018 and December 30, 2017:



	Amortized Cost				Unrealized (Losses) Gains						Fair Value
	2018		2017		2018			2017			2018		2017
U.S. government and agency backed securities	$	16,070,511	$	35,014,593	$	(414,404	)	$	(288,782	)	$	15,656,107	$	34,725,811
Corporate debt	11,178,825		8,988,608		1,036			(7,702		)	11,179,861		8,980,906
Certificates of deposit	—		201,000		—			(260		)	—		200,740
Total	$	27,249,336	$	44,204,201	$	(413,368	)	$	(296,744	)	$	26,835,968	$	43,907,457

The contractual maturity of the Company’s marketable debt securities was as follows at September 29, 2018:



	Less than One year		One to Five years		Greater than Five years		Total
U.S. government and agency backed securities	$	6,223,207	$	9,432,900	$	—	$	15,656,107
Corporate debt	3,213,495		7,966,366		—		11,179,861
Total	$	9,436,702	$	17,399,266	$	—	$	26,835,968

The Company conducts a review of its marketable debt securities on a quarterly basis for the presence of other-than-temporary impairment ("OTTI"). The Company assesses whether OTTI is present when the fair value of a debt security is less than its amortized cost basis at the balance sheets date. Under these circumstances OTTI is considered to have occurred if (1) the Company intends to sell the security before recovery of its amortized cost basis; (2) it is “more likely than not” the Company will be required to sell the security before recovery of its amortized cost basis; or (3) the present value of expected cash flows is not sufficient to recover the entire amortized cost basis.

The Company further estimates the amount of OTTI resulting from a decline in the creditworthiness of the issuer (credit-related OTTI) and the amount of non credit-related OTTI. Non-credit-related OTTI can be caused by such factors as market illiquidity. Credit-related OTTI is recognized in earnings while non-credit-related OTTI on securities not expected to be sold is recognized in other comprehensive income (loss). The Company did not record OTTI for the three and nine months ended September 29, 2018 and September 30, 2017.