The Company established an Employee Share Purchase Plan to provide each employee and trustee the ability to annually acquire up to $100,000 of Common Shares of EQR. The Company registered 7,000,000 Common Shares under the ESPP, of which 2,714,332 Common Shares remained available for purchase at December 31, 2019. The Common Shares may be purchased quarterly at a price equal to 85% of the lesser of: (a) the closing price for a share on the last day of such quarter; and (b) the greater of: (i) the closing price for a share on the first day of such quarter, and (ii) the average closing price for a share for all the business days in the quarter. The following table summarizes information regarding the Common Shares issued under the ESPP with the net proceeds noted below being contributed to ERPOP in exchange for OP Units (amounts in thousands except share and per share amounts):

	Year Ended December 31,
	2019		2018		2017
Shares issued		48,131		75,414		68,286
Issuance price ranges	$59.56 – $72.91		$47.80 – $57.09		$52.79 – $58.06
Issuance proceeds		$3,116	$3,879		$3,744

The Company established a defined contribution plan (the “401(k) Plan”) to provide retirement benefits for employees that meet minimum employment criteria. The Company matches dollar for dollar up to the first 4% of eligible compensation that a participant contributes to the 401(k) Plan for all employees except those defined as highly compensated employees, whose match is 3%. Participants are vested in the Company’s contributions over five years. The Company recognized an expense in the amount of $5.0 million, $4.9 million and $4.6 million for the years ended December 31, 2019, 2018 and 2017, respectively.

The Company established the SERP to provide certain officers and trustees an opportunity to defer a portion of their eligible compensation in order to save for retirement. The SERP is restricted to investments in Common Shares, certain marketable securities that have been specifically approved and cash equivalents. The deferred compensation liability represented in the SERP and the securities issued to fund such deferred compensation liability are consolidated by the Company and carried on the Company’s balance sheets, and the Company’s Common Shares held in the SERP are accounted for as a reduction to paid in capital (included in general partner’s capital in the Operating Partnership’s financial statements).