We maintain an incentive stock plan and a wealth accumulation plan (“the Plan”) that provides for the granting of stock options, stock appreciation rights, restricted stock, performance awards, stock units, and debentures (collectively, “deferred awards”) to our associates. We are permitted to issue new shares under all stock award plans approved by shareholders or to reissue our treasury shares. Stock awards issued under our company’s incentive stock plan are granted at market value at the date of grant. Our deferred awards generally vest ratably over a one- to ten-year vesting period.

Our stock-based compensation plans are administered by the Compensation Committee of the Board of Directors (“Compensation Committee”), which has the authority to interpret the plans, determine to whom awards may be granted under the plans, and determine the terms of each award. According to the incentive stock plan, we are authorized to grant an additional 3.3 million shares at December 31, 2019.

Compensation expense associated with our stock-based compensation plans, included in compensation and benefits in the consolidated statements of operations for our company’s incentive stock award plans was $135.5 million, $111.8 million, and $246.7 million for the years ended December 31, 2019, 2018, and 2017, respectively.

The tax benefit related to stock-based compensation was $11.9 million and $4.0 million for the years ended December 31, 2019 and 2018, respectively. As a result of the adoption of a new accounting standard on January 1, 2017, we recognized an excess tax benefit from stock-based compensation of $64.7 million for the year ended December 31, 2017.

In response to the Tax Legislation that was enacted in December 2017, the Company offered certain associates the opportunity to participate in the conversion of certain restricted stock units into restricted stock pursuant to a Modification Award Agreement. Under the terms of the Modification Award Agreement, vesting of certain restricted stock will no longer be contingent upon continued employment but rather will vest so long as the associate is not engaged in certain competitive or soliciting activities as provided in the Wealth Accumulation Plan (the “Plan”). The conversion through acceptance of the Modification Agreement by the participating associates resulted in a charge of $55.9 million, which is included in compensation and benefits in the consolidated statement of operations for the year ended December 31, 2017. The fair value of these awards was based upon the closing price of our company’s common stock on the date of the grant of the awards.

In December 2017, the Company accelerated the vesting of certain outstanding debenture awards, resulting in a charge of $51.4 million, which is included in compensation and benefits in the consolidated statement of operations for the year ended December 31, 2017.

A restricted stock unit represents the right to receive a share of the Company’s common stock at a designated time in the future without cash payment by the associate and is issued in lieu of cash incentive, principally for deferred compensation and employee retention plans. The restricted stock units vest on an annual basis over the next one to ten years and are distributable, if vested, at future specified dates. Restricted stock awards are restricted as to sale or disposition. These restrictions lapse over the next one to five years.

Our company grants Performance-based Restricted Stock Units (“PRSUs”) to certain of its executive officers. Under the terms of the grants, the number of PRSUs that will vest and convert to shares will be based on our company’s achievement of the pre-determined performance objectives during the performance period. The PRSUs will be measured over a four-year performance period and vested over a five-year period. Any resulting delivery of shares for PRSUs granted as part of compensation will occur after four years for 80% of the earned award, and in the fifth year for the remaining 20% of the earned award. The number of shares converted has the potential to range from 0% to 200% based on how the Company performs during the performance period. Compensation expense is amortized on a straight-line basis over the service period based on the fair value of the award on the grant date. The Company’s pre-determined performance objectives must be met for the awards to vest. Associates forfeit unvested share units upon termination of employment with a corresponding reversal of compensation expense. At December 31, 2019, the total number of restricted stock units, PRSUs, and restricted stock awards outstanding was 15.6 million, of which 13.5 million were unvested.

A summary of unvested restricted equity award activity, which includes restricted stock units and restricted stock awards, for the year ended December 31, 2019, is presented below (in thousands, except weighted-average fair value):

			Weighted-average grant date fair value
Unvested December 31, 2018	14,117		$	46.75
Granted	2,871			49.60
Vested	(2,656	)		45.34
Cancelled	(864	)		43.87
Unvested December 31, 2019	13,468		$	47.83

At December 31, 2019, there was approximately $448.4 million of unrecognized compensation cost for deferred awards, which is expected to be recognized over a weighted-average period of 2.8 years.

The fair value of restricted stock units and restricted stock that vested or converted during the year ended December 31, 2019, was $120.4 million.

The Plan is provided to certain revenue producers, officers, and key administrative associates, whereby a certain percentage of their incentive compensation is deferred as defined by the Plan into company stock units, restricted stock, and debentures. Participants may elect to defer a portion of their incentive compensation. Deferred awards generally vest over a one- to ten-year period and are distributable upon vesting or at future specified dates. Deferred compensation costs are amortized on a straight-line basis over the vesting period. Elective deferrals are 100% vested.

Additionally, the Plan allows Stifel financial advisors who achieve certain levels of production the option to defer a certain percentage of their gross commissions. As stipulated by the Plan, the financial advisors will defer 5% of their gross commissions. The mandatory deferral will be split evenly between company restricted stock units and a company fixed-rate cash debenture. They have the option to defer an additional 1% of gross commissions into company stock units with a 25% matching contribution.

In addition, certain financial advisors, upon joining our company, may receive company stock units in lieu of transition cash payments. Deferred compensation related to these awards generally vests over a one- to eight-year period. Deferred compensation costs are amortized on a straight-line basis over the deferral period.

Eligible U.S. associates of our company who have met certain service requirements may participate in the Stifel Financial Corp. Profit Sharing 401(k) Plan (the “Plan”). Associates are permitted within limitations imposed by tax law to make pre-tax contributions to the Plan. We may match certain associate contributions or make additional contributions to the Plan at our discretion. Our contributions to profit sharing, included in compensation and benefits in the consolidated statements of operations, were $13.4 million, $12.8 million, and $7.1 million for the years ended December 31, 2019, 2018, and 2017, respectively.