Fair Value Measurements

The following tables present the financial instruments that were measured at fair value on a recurring basis at March 31, 2018 and December 31, 2017 by level within the fair value hierarchy (in thousands):



	March 31, 2018
	Level 1		Level 2		Level 3		Total
Money market funds ⁽¹⁾	$	6,801	$	—	$	—	$	6,801
Common shares of CO2 Solutions ⁽²⁾	—		697		—		697
Total	$	6,801	$	697	$	—	$	7,498



	December 31, 2017
	Level 1		Level 2		Level 3		Total
Money market funds ⁽¹⁾	$	6,778	$	—	$	—	$	6,778
Common shares of CO2Solutions ⁽²⁾	—		671		—		671
Total	$	6,778	$	671	$	—	$	7,449

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

(2) Common shares of CO₂ Solutions are classified as marketable securities, and included in non-current assets on our unaudited condensed consolidated balance sheets.

We determine the fair value of Level 1 assets using quoted prices in active markets for identical assets. We estimated the fair value of our investment in 10,000,000 common shares of CO₂ Solutions using the market value of common shares as determined by trading on the TSX Venture Exchange, and we classified our investment in CO₂ Solutions as Level 2 assets due to the volatile and low trading volume. There were no transfers between Level 1 and Level 2 securities in the periods presented. (See also Note 6, "Cash Equivalents and Marketable Securities.")

During the three months ended March 31, 2018, unrealized gains related to our investment in CO₂ Solutions was $26 thousand and was included in other expense, net, in the unaudited condensed consolidated statements of operations. Prior to our adoption of ASU 2016-01, we recorded unrealized gains and losses from our investment in CO₂ Solutions in accumulated other comprehensive loss in stockholders' equity. During the three months ended March 31, 2017, unrealized losses related to our investment in CO₂ Solutions was $0.1 million and was included in other comprehensive loss.