7. Employee Benefit Plans

We maintain the Chipotle Mexican Grill 401(k) Plan (the “401(k) Plan”). We match 100% of the first 3% of pay contributed by each eligible employee and 50% on the next 2% of pay contributed. Employees become eligible to receive matching contributions after one year of service with the Company. For the years ended December 31, 2017, 2016, and 2015, matching contributions totaled approximately $6,072, $5,939 and $4,995, respectively.

We also maintain the Chipotle Mexican Grill, Inc. Supplemental Deferred Investment Plan (the “Deferred Plan”) which covers our eligible employees. The Deferred Plan is a non-qualified plan that allows participants to make tax-deferred contributions that cannot be made under the 401(k) Plan because of Internal Revenue Service limitations. Participants’ earnings on contributions made to the Deferred Plan fluctuate with the actual earnings and losses of a variety of available investment choices selected by the participant. Total liabilities under the Deferred Plan as of December 31, 2017 and 2016 were $19,887 and $17,843, respectively, and are included in other liabilities in the consolidated balance sheet. We match 100% of the first 3% of pay contributed by each eligible employee and 50% on the next 2% of pay contributed once the 401(k) contribution limits are reached. For the years ended December 31, 2017, 2016, and 2015, we made deferred compensation matches of $199, $225, and $617, respectively, to the Deferred Plan.

We have elected to fund our deferred compensation obligation through a rabbi trust. The rabbi trust is subject to creditor claims in the event of insolvency, but the assets held in the rabbi trust are not available for general corporate purposes. Amounts in the rabbi trust are invested in mutual funds, consistent with the investment choices selected by participants in their Deferred Plan accounts, which are designated as trading securities and carried at fair value, and are included in other assets in the consolidated balance sheet. Fair value of mutual funds is measured using Level 1 inputs (quoted prices for identical assets in active markets), and the fair values of the investments in the rabbi trust were $19,887 and $17,843 as of December 31, 2017 and 2016, respectively. Trading gains and losses are recorded in general and administrative expenses in the consolidated statement of income, along with the offsetting amount related to the increase or decrease in deferred compensation to reflect its exposure of the Deferred Plan liability.

The following table sets forth unrealized gains (losses) on trading securities held in the rabbi trust:



	Year ended December 31,
	2017		2016		2015
Unrealized gains (losses) on trading securities held in rabbi trust	$	1,520	$	586	$	(571)

We also offer an employee stock purchase plan (“ESPP”). Employees become eligible to participate after one year of service with Chipotle and may contribute up to 15% of their base earnings, subject to an annual maximum dollar amount, toward the monthly purchase of our common stock. Under the ESPP, 250 shares of common stock have been authorized and reserved for issuances to eligible employees, of which 246 represent shares that were authorized for issuance but not issued at December 31, 2017. For each of the years ended December 31, 2017, 2016, and 2015, the number of shares issued under the ESPP were less than 1.