The amortized cost and fair value of marketable securities as of September 30, 2020 and 2019 were as follows:

(in thousands)

September 30, 2020

Amortized

cost

Gross

unrealized

gains

Gross

unrealized

losses

Fair value

Corporate notes/bonds

58,793

323

(17

)

59,099

(in thousands)	September 30, 2019
	Amortized cost		Gross unrealized gains		Gross unrealized losses			Fair value
Commercial paper	$	999	$	—	$	—		$	999
Corporate notes/bonds		56,318		146		(28	)		56,436
	$	57,317	$	146	$	(28	)	$	57,435

The following tables summarize the fair value and gross unrealized losses aggregated by category and the length of time that individual securities have been in a continuous unrealized loss position as of September 30, 2020 and 2019.

(in thousands)	September 30, 2020
	Less than twelve months					Greater than twelve months				Total
	Fair value		Gross unrealized loss			Fair value		Gross unrealized loss		Fair value		Gross unrealized loss
Corporate notes/bonds	$	9,841	$	(17	)	$	—	$	—	$	9,841	$	(17	)

(in thousands)	September 30, 2019
	Less than twelve months					Greater than twelve months					Total
	Fair value		Gross unrealized loss			Fair value		Gross unrealized loss			Fair value		Gross unrealized loss
Corporate notes/bonds	$	12,419	$	(14	)	$	16,369	$	(14	)	$	28,788	$	(28	)

The following table presents our available-for-sale marketable securities by contractual maturity date as of September 30, 2020 and 2019.

(in thousands)	September 30, 2020				September 30, 2019
	Amortized cost		Fair value		Amortized cost		Fair value
Due in one year or less	$	27,727	$	27,899	$	27,725	$	27,735
Due after one year through three years		31,066		31,200		29,592		29,700
	$	58,793	$	59,099	$	57,317	$	57,435