4. Investments

The following is a summary of investments as of December 31, 2018 and 2017. At December 31, 2018, the Company transferred its investments from available-for-sale classification to trading, due to the Company's decision to liquidate all investments to complete a significant business combination, that occurred in the first quarter of 2019. See Note 14 for further discussion on the subsequent event. As a result of the transfer to trading, the Company recorded a loss of $372 in investment interest and other for the year ended December 31, 2018 and there was no unrealized gain or loss as of December 31, 2018. Prior to December 2018, the Company considered all investments as available for sale.


	As of December 31, 2018
			Gross		Gross		Estimated
	Adjusted		Unrealized		Unrealized		Fair
	Cost		Gains		(Losses)		Value
Municipal securities	$	69,002	$	—	$	—	$	69,002

Total investments	$	69,002	$	—	$	—	$	69,002


	As of December 31, 2017
			Gross		Gross
	Adjusted		Unrealized		Unrealized		Estimated
	Cost		Gains		(Losses)		Fair Value
Municipal securities	$	84,768	$	—	$	(409)	$	84,359
Certificates of Deposit	$	4,915	$	—	$	(3)	$	4,912

Total investments	$	89,683	$	—	$	(412)	$	89,271

The cash flows of municipal securities are backed by the issuing municipality’s credit worthiness. All municipal securities and certificates of deposit are due in one year or less as of December 31, 2018. For the years ended December 31, 2018 and 2017, the net unrealized losses on available-for-sale securities were $0 and $255, net of taxes, respectively.