The Company classifies its short-term investments as available-for-sale securities. Available-for-sale securities are carried at fair market value with net unrealized gains and losses reported as a component of accumulated other comprehensive loss in stockholders’ equity. No realized gains or losses were recognized during the three and six months ended March 31, 2021 and 2020.

The Company’s short-term investments were composed of the following (in thousands):

	As of March 31, 2021 (in thousands)
	Amortized Cost		Unrealized Gains			Unrealized Losses		Estimated Fair Value
Short-term investments:
Corporate bonds	$	3,868	$	(3	)	$	—	$	3,865

The Company’s short-term investments had contractual maturities ranging from September 2021 to May 2022.

On July 13, 2020, the Company received an interest in a senior secured bond issued from an international seismic marine customer. The Company’s interest in the bond, which has a face value of $13.0 million, was received in exchange for $13.0 million of unpaid invoices and late fees owed by the customer. The bond is secured by a third in line lien on the assets owned by the customer and has an 8% interest rate with bi-annual interest and possible principal payments based on available excess cash flows. Interest payments can be made either in cash or in-kind payments in the form of additional debt security. In-kind interest payments require an 8.8% interest rate. The bond matures on July 13, 2022. The bond is listed on the Oslo Alternative Bond Market; however, the actual marketability of the bond is unknown at this time.

Upon receipt of the senior secured bond, the Company performed a fair value assessment of the investment to determine the bond’s initial carrying amount. In accordance with ASC 825, “Fair Value Instruments”, the Company has determined that the investment is a Level 3 financial instrument primarily due to its current unknown marketability. Because of the distressed financial condition of the customer, the Company believes the fair value of the bond is nominal.

In January 2021, the Company transferred the security pursuant to a purchase agreement (the “Agreement”) entered with a third party (the “Buyer”). Pursuant to the Agreement, the Company received non-refundable consideration of $0.3 million and will receive additional cash compensation of $2.4 million from the Buyer if certain terms and conditions between the Buyer and the Company’s customer are met by December 31, 2021. In the event these terms and conditions are not met, the Company has the option to reacquire the bond from the Buyer for one dollar US ($1.00). The Company recognized a gain on investment of $0.3 million during the three months ended March 31, 2021 in connection with the transfer of the bond.