Fair Value Measurements

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



	December 31, 2018
	Level 1		Level 2		Level 3		Total
Money market funds	$	31,225	$	—	$	—	$	31,225
Common shares of CO₂ Solutions	588		—		—		588
Total	$	31,813	$	—	$	—	$	31,813



	December 31, 2017
	Level 1		Level 2		Level 3		Total
Money market funds	$	6,778	$	—	$	—	$	6,778
Common shares of CO₂ Solutions	—		671		—		671
Total	$	6,778	$	671	$	—	$	7,449

We determine the fair value of Level 1 and Level 2 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 CO₂Solutions within the fair value hierarchy as Level 1 and Level 2, at December 31, 2018 and December 31, 2017, respectively, using the quoted prices in an active market to determine their fair value.

A review of the fair value hierarchy classifications of our investments is conducted annually. Changes in the observability of valuation inputs may result in a reclassification for certain financial assets. Reclassifications are reported as transfers in or transfers out of the applicable level at end of the calendar year in which the reclassifications occur. In the fourth quarter of 2018, we reclassified the $0.6 million fair value of the investment in the common shares of CO₂ Solutions from Level 2 to Level 1 within the fair value hierarchy since we concluded that there was a sufficient level of transactional frequency and trading volume to indicate that the pricing information was representative of its fair value on an ongoing basis. (See also Note 6, “Cash Equivalents and Equity Securities” for additional information.)