Note 4 — Investments

At December 31, 2017 and 2016 the amortized cost and fair value of marketable securities were as follows:

			Gross		Gross
	Amortized		Unrealized		Unrealized			Estimated
	Cost		Gains		Losses			Fair Value
	(in thousands)
December 31, 2017
U.S. treasuries	$	33,914	$	—	$	(19	)	$	33,895
Corporate debt	10,894		—		(8		)	10,886
Commercial paper	2,999		—		—			2,999

Total	$	47,807	$	—	$	(27	)	$	47,780


December 31, 2016
U.S. treasuries	$	40,013	$	—	$	(5	)	$	40,008
Government agency securities	10,020		—		(8		)	10,012
Corporate debt	13,780		—		(7		)	13,773
Commercial paper	2,994		—		—			2,994

Total	$	66,807	$	—	$	(20	)	$	66,787

Available-for-sale securities in a loss position at December 31, 2017 and 2016 were as follows:

	December 31, 2017					December 31, 2016
			Gross					Gross
	Estimated		Unrealized			Estimated		Unrealized
	Fair Value		Losses			Fair Value		Losses
	(in thousands)
U.S. treasuries	$	33,895	$	(19	)	$	20,002	$	(5	)
Government agency securities	—		—			10,012		(8		)
Corporate debt	10,886		(8		)	13,773		(7		)

Total	$	44,781	$	(27	)	$	43,787	$	(20	)

At December 31, 2017 and 2016, there were no short-term investments that had been in a continuous loss position for more than 12 months.

The maturities of securities classified as available-for-sale at December 31, 2017 were all due in one year or less. Actual maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties. There were minimal realized gains or losses for the years ended December 31, 2017, 2016, and 2015.

Cost Method Investment

The Company has an ownership interest of less than 20% in a non-marketable investment, Kateeva, Inc. (“Kateeva”). The Company does not exert significant influence over Kateeva and therefore the investment is carried at cost. The carrying value of the investment was $21.0 million at December 31, 2017 and 2016. The investment is included in “Other assets” on the Consolidated Balance Sheets. The investment is subject to a periodic impairment review; as there are no open-market valuations, the impairment analysis requires judgment. The analysis includes assessments of Kateeva’s financial condition, the business outlook for its products and technology, its projected results and cash flow, business valuation indications from recent rounds of financing, the likelihood of obtaining subsequent rounds of financing, and the impact of equity preferences held by Veeco relative to other investors. Fair value of the investment is not estimated unless there are identified events or changes in circumstances that could have a significant adverse effect on the fair value of the investment. No such events or circumstances are present.