3. Investments

Investments consist of the following:


	April 30,
	2018		2017
	(In thousands)
Short-term investments:
Held-to-maturity securities:
Municipal securities	$	35,344	$	47,437
U.S. government securities		31,620		14,515
Corporate bonds		46,685		55,519
Certificates of deposit		—		2,500
Total held-to-maturity and short-term investments	$	113,649	$	119,971
Long-term investments:
Held-to-maturity securities:
Municipal securities	$	2,046	$	8,942
U.S. government securities		27,356		22,540
Corporate bonds		9,112		8,117
Total held-to-maturity investments		38,514		39,599
Available-for-sale securities:
Auction rate securities		2,142		2,497
Total available-for-sale investments		2,142		2,497
Total long-term investments	$	40,656	$	42,096

Held‑To‑Maturity Securities

As of April 30, 2018 and 2017, the balance of held‑to‑maturity securities consisted of state and local government municipal securities, U.S. government securities, corporate bonds and certificates of deposit. Interest earned from these investments is recorded in interest income.

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


	April 30, 2018								April 30, 2017
			Gross		Gross						Gross		Gross
	Amortized		Unrealized		Unrealized		Fair		Amortized		Unrealized		Unrealized		Fair
	Cost		Gains		Losses		Value		Cost		Gains		Losses		Value
Municipal securities	$	37,390	$	9	$	(36)	$	37,363	$	56,379	$	30	$	(21)	$	56,388
U.S. government securities		58,976		—		(367)		58,609		37,055		2		(41)		37,016
Corporate bonds		55,797		2		(71)		55,728		63,636		9		(85)		63,560
Certificates of deposit		—		—		—		—		2,500		1		—		2,501
Total held-to-maturity investments	$	152,163	$	11	$	(474)	$	151,700	$	159,570	$	42	$	(147)	$	159,465

The amortized cost and fair value of the Company’s held‑to‑maturity securities by contractual maturity at April 30, 2018, are as follows:


	Cost		Fair Value
Due within one year	$	113,649	$	113,443
Due after one year through five years		38,514		38,257
Total	$	152,163	$	151,700

Available‑For‑Sale Securities

Auction Rate Securities

As of April 30, 2018 and 2017, the entire balance of available‑for‑sale auction rate securities consisted of two investment grade auction rate municipal bonds with maturities ranging from 1 to 16 years. 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 April 30, 2018 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 April 30, 2018 and 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 expectation of the next time 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 the current lack of liquidity on these investments will affect its ability to operate the 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 maturity and as of April 30, 2018, it did not consider these investments to be other‑than‑temporarily impaired.

The amortized cost, gross unrealized losses, and estimated fair value of the available‑for‑sale auction rate securities are as follows (in thousands):


	April 30,
	2018		2017
Auction rate securities
Amortized cost	$	2,250	$	2,700
Gross unrealized losses		(108)		(203)
Fair value	$	2,142	$	2,497

The amortized cost and fair value of the Company’s auction rate securities by contractual maturity at April 30, 2018 are as follows (in thousands):


	Cost		Fair Value
Due after one through five years	$	250	$	252
Due after 10 years		2,000		1,890
Total	$	2,250	$	2,142

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), net 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. During the fiscal year ended April 30, 2016, the Company realized gains on the sale of CybAero shares 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.