2. Investments

Investments consist of the following (in thousands):


	January 28,		April 30,
	2017		2016

Short-term investments:
Held-to-maturity securities:
Municipal securities	$	40,211	$	42,179
U.S. government securities		19,720		21,184
Corporate bonds		56,664		40,041
Certificates of deposit		4,500		—
Total held-to-maturity and short-term investments	$	121,095	$	103,404
Long-term investments:
Held-to-maturity securities:
Municipal securities	$	15,446	$	—
U.S. government securities		15,549		7,518
Corporate bonds		10,336		23,561
Total held-to-maturity investments		41,331		31,079
Available-for-sale securities:
Auction rate securities		2,418		2,780
Total available-for-sale investments		2,418		2,780
Total long-term investments	$	43,749	$	33,859

Held-To-Maturity Securities

As of January 28, 2017 and April 30, 2016, the balance of held-to-maturity securities consisted of state and local government municipal securities, U.S. treasury and agency securities, certificates of deposit and corporate bonds. Interest earned from these investments is recorded in interest income.

The amortized cost, gross unrealized gains, gross unrealized losses, and estimated fair value of the held-to-maturity investments as of January 28, 2017, were as follows (in thousands):


			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Municipal securities	$	55,657	$	25	$	(43)	$	55,639
U.S. government securities		35,269		5		(13)		35,261
Corporate bonds		67,000		2		(113)		66,889
Certificates of deposit		4,500		3		—		4,503
Total held-to-maturity investments	$	162,426	$	35	$	(169)	$	162,292

The amortized cost, gross unrealized gains, gross unrealized losses, and estimated fair value of the held-to-maturity investments as of April 30, 2016, were as follows (in thousands):


			Gross		Gross
	Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value
Municipal securities	$	42,179	$	5	$	(7)	$	42,177
U.S. government securities		28,702		23		—		28,725
Corporate bonds		63,602		54		(32)		63,624
Certificates of deposit		—		—		—		—
Total held-to-maturity investments	$	134,483	$	82	$	(39)	$	134,526

The amortized cost and fair value of the held-to-maturity securities by contractual maturity at January 28, 2017, were as follows (in thousands):


	Cost		Fair Value
Due within one year	$	121,095	$	121,031
Due after one year through five years		41,331		41,261
Total	$	162,426	$	162,292

Available-For-Sale Securities

Auction Rate Securities

As of January 28, 2017 and April 30, 2016, the entire balance of available-for-sale, auction rate securities, consisted of two investment grade auction rate municipal bonds, with maturities of approximately 2 and 17 years, respectively. These investments have characteristics similar to short-term investments, because at pre-determined intervals, generally ranging from 30 to 35 days, there is a new auction process at which the interest rates for these securities are reset to current interest rates. At the end of such period, the Company chooses to roll-over its holdings or redeem the investments for cash. A market maker facilitates the redemption of the securities and the underlying issuers are not required to redeem the investment within 365 days. Interest earned from these investments is recorded in interest income.

During the fourth quarter of the fiscal year ended April 30, 2008, the Company began experiencing failed auctions on some of its auction rate securities. A failed auction occurs when a buyer for the securities cannot be obtained and the market maker does not buy the security for its own account. The Company continues to earn interest on the investments that failed to settle at auction, at the maximum contractual rate until the next auction occurs. In the event the Company needs to access funds invested in these auction rate securities, the Company may not be able to liquidate these securities at the fair value recorded on January 28, 2017, until a future auction of these securities is successful or a buyer is found outside of the auction process.

As a result of the failed auctions, the fair values of these securities are estimated utilizing a discounted cash flow analysis as of January 28, 2017. The analysis considers, among other items, the collateralization underlying the security investments, the creditworthiness of the counterparty, the timing of expected future cash flows, and the estimated date upon which the security is expected to have a successful auction. Based on the Company’s ability to access its cash and cash equivalents, expected operating cash flows, and other sources of cash, the Company does not anticipate that the current lack of liquidity of these investments will affect its ability to operate its business in the ordinary course. The Company believes the current lack of liquidity of these investments is temporary and expects that the securities will be redeemed or refinanced at some point in the future. The Company will continue to monitor the value of its auction rate securities at each reporting period for a possible impairment if a further decline in fair value occurs. The auction rate securities have been in an unrealized loss position for more than 12 months. The Company has the ability and the intent to hold these investments until a recovery of fair value, which may be at maturity and as of January 28, 2017, the Company did not consider these investments to be other-than-temporarily impaired.

The amortized cost, gross unrealized gains, gross unrealized losses, and estimated fair value of the auction rate securities as of January 28, 2017, were as follows (in thousands):


			Gross		Gross
	Amortized		Unrealized		Unrealized
	Cost		Gains		Losses		Fair Value
Auction rate securities	$	2,700	$	—	$	(282)	$	2,418
Total available-for-sale investments	$	2,700	$	—	$	(282)	$	2,418

The amortized cost, gross unrealized gains, gross unrealized losses, and estimated fair value of the auction rate securities as of April 30, 2016, were as follows (in thousands):


			Gross		Gross
	Amortized		Unrealized		Unrealized
	Cost		Gains		Losses		Fair Value
Auction rate securities	$	3,100	$	—	$	(320)	$	2,780
Total available-for-sale investments	$	3,100	$	—	$	(320)	$	2,780

The amortized cost and fair value of the auction rate securities by contractual maturity at January 28, 2017, were as follows (in thousands):


	Cost		Fair Value
Due after one through five years	$	700	$	677
Due after 10 years		2,000		1,741
Total	$	2,700	$	2,418

Equity Securities

At April 30, 2015, the entire balance of available-for-sale equity securities consisted of 618,042 CybAero AB (“CybAero”) common shares. The shares were classified as available-for-sale. These shares were initially acquired on August 11, 2014, when the Company converted a convertible bond into CybAero common shares. The convertible bond was in the amount of 10 million SEK and was converted into 1,062,699 common shares of CybAero at the conversion price of 9.41 SEK per share. When the Company converted the bond on August 11, 2014, the fair value per share was 37.50 SEK which became the new cost basis going forward, with all subsequent changes in fair value being recorded to other comprehensive income.

At August 1, 2015, the Company reviewed these shares for impairment based on criteria that included the extent to which the investment’s carrying value exceeds its related market value, the duration of the market decline, uncertainty as to the recovery period due to sustained losses of the investee and the Company’s intent to hold its investment until recovery. In the three months ended August 1, 2015, the Company determined it was in its best interests to liquidate the remaining shares held. As a result, during the three months ended August 1, 2015, the Company recorded an other‑than‑temporary-impairment loss of $2,186,000 related to the Company’s investment in the CybAero shares which was recorded to Other expense in the consolidated statement of operations. As a result of recording the impairment charge, the investment’s fair value became its new cost basis.

In August 2015, the Company sold its remaining shares in CybAero in a private sale at the price of 12.00 SEK per share, resulting in proceeds of approximately $777,000 resulting in realized gains of $207,000, based on the difference between the original conversion price of 9.41 SEK per share and the sales price at the time of sale, inclusive of the final sale of all shares.