Long-term incentive program (LTIP) compensation includes both stock-based awards (principally stock-settled stock appreciation rights, restricted stock units and performance stock units) and long-term performance-based cash awards. Long-term incentive compensation expense, which is primarily general and administrative in nature, is attributed to the Company’s U.S. dialysis business, its corporate administrative support, and its ancillary services.

The Company’s stock-based compensation expense for stock-settled awards is measured at the estimated fair value of awards on the date of grant and recognized on a cumulative straight-line basis over the vesting terms of the awards, unless the stock awards are based on non-market-based performance metrics, in which case expense is adjusted for the ultimate number of shares expected to be issued as of the end of each reporting period. Stock-based compensation expense for cash-settled awards is based on their estimated fair values as of the end of each reporting period. The expense for all stock-based awards is recognized net of expected forfeitures.

Stock-based compensation to be settled in shares is recorded to the Company’s shareholders’ contributed capital, while stock-based compensation to be settled in cash is recorded to a liability. Shares issued upon exercise of stock awards are issued from authorized but unissued shares.

The Company’s 2011 Incentive Award Plan (the 2011 Plan) is the Company’s omnibus equity compensation plan and provides for grants of stock-based awards to employees, directors and other individuals providing services to the Company, except that incentive stock options may only be awarded to employees. The 2011 Plan authorizes the Company to award stock options, stock appreciation rights, restricted stock units, restricted stock, and other stock-based or performance-based awards. The 2011 Plan mandates a maximum award term of five years and stipulates that stock appreciation rights and stock options be granted with prices not less than fair market value on the date of grant. The 2011 Plan also requires that full value share awards such as restricted stock units reduce shares available under the 2011 Plan at a ratio of 3.5:1. The Company’s nonqualified stock appreciation rights and stock units awarded under the 2011 Plan generally vest over 36 months to 48 months from the date of grant. At December 31, 2019, there were 15,547 shares available for future grants under the 2011 Plan. This number of shares available does not reflect reduction for the Premium Priced Award described below, as that Board-approved award remained contingent on stockholder approval of an amendment to the 2011 Plan which did not occur until January 2020.



	Year ended December 31, 2019
	Stock appreciation rights						Stock units
	Awards			Weighted average exercise price		Weighted average remaining contractual life	Awards			Weighted average remaining contractual life
Outstanding at beginning of year	6,163			$	69.90		1,860
Granted ^{(1) ( 2)}	2,389			$	52.45		1,961
Exercised	(20		)	$	64.17		(225		)
Expired	(1,058		)	$	70.97		—
Canceled	(521		)	$	65.23		(436		)
Outstanding at end of period ⁽¹⁾	6,953			$	64.10	3.0	3,160			2.3
Exercisable at end of period	1,254			$	77.68	1.1	—			—
Weighted-average fair value of grants
2019	$	14.04					$	50.58
2018	$	16.24					$	66.23
2017	$	14.51					$	65.73



	Awards Outstanding	Weighted average exercise price		Awards exercisable	Weighted average exercise price
Range of SSARs base prices	Awards Outstanding	Weighted average exercise price		Awards exercisable	Weighted average exercise price
$50.01–$60.00	2,400	$	52.63	—	$	—
$60.01–$70.00	3,069	$	66.16	186	$	65.92
$70.01–$80.00	925	$	75.28	509	$	75.50
$80.01–$90.00	559	$	83.59	559	$	83.59
Total	6,953	$	64.10	1,254	$	77.68

For the years ended December 31, 2019, 2018, and 2017, the aggregate intrinsic value of stock-based awards exercised was $11,475, $31,045 and $34,895, respectively. At December 31, 2019, the aggregate intrinsic value of stock-based awards outstanding was $319,486 and the aggregate intrinsic value of stock awards exercisable was $1,783.

The Company has estimated the grant-date fair value of stock-settled stock appreciation rights awards using the Black-Scholes-Merton valuation model and stock-settled stock unit awards at intrinsic value on the date of grant, except for portions of the Company’s performance stock unit awards for which a Monte Carlo simulation was used to estimate the grant-date fair value. The following assumptions were used in estimating these values and determining the related stock-based compensation expense attributable to the current period:

Expected term of the awards: The expected term of awards granted represents the period of time that they are expected to remain outstanding from the date of grant. The Company determines the expected term of its stock awards based on its historical experience with similar awards, considering the Company’s historical exercise and post-vesting termination patterns, and the terms expected by peer companies in near industries.

Expected volatility: Expected volatility represents the volatility anticipated over the expected term of the award. The Company determines the expected volatility for its awards based on the volatility of the price of its common stock over the most recent retrospective period commensurate with the expected term of the award, considering the volatility expectations implied by the market price of its exchange-traded options and the volatilities expected by peer companies in near industries.

On November 4, 2019, the independent members of the Company’s Board of Directors (Board) approved an award of 2,500 premium-priced stock-settled stock appreciation rights (Premium-Priced Award) to the Company’s Chief Executive Officer (CEO), which award was subject to stockholder approval of a related amendment to the 2011 Plan. Stockholders approved such amendment to the 2011 Plan on January 23, 2020, authorizing the grant to our CEO. Since stockholder approval occurred in 2020, this award was treated as granted in 2020 for accounting purposes.

The base price of the Premium-Priced Award was $67.80 per share, which was a 20% premium to the clearing price of the Company's recent modified Dutch auction tender offer (Tender Offer). The award vests 50% on each of November 4, 2022 and November 4, 2023 and expires on November 4, 2024. The award includes a requirement that the CEO hold any shares acquired upon exercise of this award, net of shares used to cover related taxes, until November 4, 2024 (that is, for the full term of the award), subject to lapse of the holding period upon a change in control of the Company or due to the CEO's death or termination due to disability.

optional lump sum payments made in advance of the first day of the purchase right period. This compensatory plan allows employees to purchase stock for the lesser of 100% of its fair market value on the first day of the purchase right period or 85% of its fair market value on the last day of the purchase right period. Purchase right periods begin on January 1 and July 1, and end on December 31. Contributions used to purchase the Company’s common stock under this plan for the 2019, 2018 and 2017 participation periods were $16,569, $17,398 and $22,131, respectively. Shares purchased pursuant to the plan’s 2019, 2018 and 2017 participation periods were 315, 398 and 360, respectively. At December 31, 2019, there were 6,411 shares remaining available for future grants under this plan.

The fair value of participants’ purchase rights was estimated as of the beginning dates of the purchase right periods using the Black-Scholes-Merton valuation model with the following weighted average assumptions for purchase right periods in 2019, 2018 and 2017, respectively: expected volatility of 28.8%, 24.2% and 22.7%; risk-free interest rates of 2.6%, 1.9% and 1.3%, and no dividends. Using these assumptions, the weighted average estimated per share fair value of each purchase right was $13.80, $17.45 and $15.19 for 2019, 2018 and 2017, respectively.

For the years ended December 31, 2019, 2018 and 2017, the Company recognized $118,513, $85,759 and $61,978, respectively, in total LTIP expense, of which $63,705, $73,582 and $34,431, respectively, was stock-based compensation expense for stock appreciation rights, stock units and discounted employee stock plan purchases, which are primarily included in general and administrative expenses. The estimated tax benefits recorded for stock-based compensation in 2019, 2018 and 2017 were $9,186, $13,591 and $7,717, respectively. As of December 31, 2019, there was $147,267 of total estimated unrecognized compensation expense for LTIP awards outstanding, including $136,818 related to stock-based compensation arrangements under the Company’s equity compensation and stock purchase plans. The Company expects to recognize the performance-based cash component of this LTIP expense over a weighted average remaining period of 0.6 years and the stock-based component of this LTIP expense over a weighted average remaining period of 1.5 years.

During the year ended December 31, 2018, the Company adopted a retirement policy (Rule of 65 policy). The Rule of 65 policy generally provides that Section 16 officers that are a minimum age of 55 with five years of continuous service with the Company receive certain benefits with respect to their outstanding equity awards upon a qualifying retirement if the sum of their age plus years of service is greater than or equal to 65. These benefits generally include accelerated vesting of restricted stock unit awards, continued vesting of stock-settled stock appreciation rights and performance stock unit awards and an exercise window from the original vest date through the original expiration date regardless of continued employment, with pro rata vesting for a Rule of 65 retirement within one year of the award grant date. The adoption of the Rule of 65 policy resulted in a $14,704 modification charge and a net acceleration of expense of $9,727 during the year ended December 31, 2018 that is included in the expense amounts reported above.

For the years ended December 31, 2019, 2018 and 2017, the Company received $2,251, $7,988 and $13,473, respectively, in actual tax benefits upon the exercise of stock awards. Since the Company issues stock-settled stock appreciation rights rather than stock options, there were no cash proceeds from stock option exercises.