Cash Equivalents and Marketable Securities

Cash equivalents and marketable securities classified as available-for-sale at December 31, 2017 and 2016 consisted of the following (in thousands):



	December 31, 2017
	Adjusted Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value		Average Contractual Maturities
									(in days)
Money market funds ⁽¹⁾	$	6,778	$	—	$	—	$	6,778	n/a
Common shares of CO₂ Solutions ⁽²⁾	563		108		—		671		n/a
Total	$	7,341	$	108	$	—	$	7,449



	December 31, 2016
	Adjusted Cost		Gross Unrealized Gains		Gross Unrealized Losses		Estimated Fair Value		Average Contractual Maturities
									(in days)
Money market funds ⁽¹⁾	$	11,172	$	—	$	—	$	11,172	n/a
Common shares of CO₂ Solutions ⁽²⁾	563		579		—		1,142		n/a
Total	$	11,735	$	579	$	—	$	12,314

⁽¹⁾Money market funds are classified in cash and cash equivalents on our consolidated balance sheets.

⁽²⁾Common shares of CO₂ Solutions are classified in marketable securities on our consolidated balance sheets.

As of December 31, 2017, the total cash and cash equivalents balance of $31.2 million was comprised of money market funds of $6.8 million and cash of $24.4 million held with major financial institutions worldwide. As of December 31, 2016, the total cash and cash equivalents balance of $19.2 million was comprised of money market funds of $11.2 million and cash of $8.0 million held with major financial institutions worldwide.

In December 2009, we purchased 10,000,000 common shares of CO₂ Solutions, a company based in Quebec, Canada, whose shares are publicly traded in Canada on TSX Venture Exchange. Our purchase represented approximately 16.6% of CO₂ Solutions’ total common shares outstanding at the time of investment and was made in a private placement subject to a four-month statutory resale restriction. This restriction expired on April 15, 2010. Our investment in CO₂ Solutions is classified as available for sale and is recorded at its fair value (See Note 6 - Fair Value Measurements). Through December 31, 2017, we concluded that we did not have the ability to exercise significant influence over CO₂ Solutions’ operating and financial policies.

As of December 31, 2017 and 2016, we had no marketable securities in an unrealized loss position.