12.  STOCK-BASED COMPENSATION

Equity Incentive Plan

The Company’s 2011 Equity Incentive Plan provides for the grant of shares of restricted stock, restricted share units, stock appreciation rights, dividend or dividend equivalent rights, stock awards and other awards valued in whole or in part by reference to or otherwise based on the Company’s common stock, to officers, employees and directors of the Company.

Restricted Stock and Restricted Stock Units

The Company grants restricted shares of common stock and restricted stock units (“RSU”) in connection with a long-term incentive plan. Awards with time-based vesting requirements vest ratably over a three-year period. Awards with performance based vesting requirements cliff vest after a three-year performance cycle and only after the achievement of certain performance criteria over that cycle.

Compensation expense recognized for restricted stock and RSUs totaled $811 and $495, respectively, for the three months ended March 30, 2019, and March 31, 2018.

The following table summarizes restricted stock and RSU activity for the three months ended March 30, 2019: 

⁽¹⁾ Approximately 34,000 performance based RSUs were granted during 2019 and are included as granted in the table above. The number of shares that ultimately vest may vary from 0% to 150% of their target vesting amount based on the achievement of defined performance targets.

The Company had $8,708 of total unrecognized compensation cost related to the restricted stock and RSU awards granted under the 2011 Plan as of March 30, 2019. That cost is expected to be recognized over a weighted average period of 2.1 years.

Employee Stock Purchase Plans

The Company maintains an Employee Stock Purchase Plan (“ESPP”) in which the U.S. employees of Helios, Sun Hydraulics and Enovation Controls are eligible to participate. Employees in the United States who choose to participate are granted an opportunity to purchase common stock at 85 percent of market value on the first or last day of the quarterly purchase period, whichever is lower. Employees in the United Kingdom, under a separate plan, are granted an opportunity to purchase the Company’s common stock at market value, on the first or last day of the quarterly purchase period, whichever is lower, with the Company issuing one additional free share of common stock for each six shares purchased by the employee under the plan. Employees purchased 14,387 shares at a weighted average price of $28.37, and 8,110 shares at a weighted average price of $45.79, under the ESPP and U.K. plans during the three months ended March 30, 2019, and March 31, 2018, respectively. The Company recognized $255 and $63 of compensation expense during the three months ended March 30, 2019, and March 31, 2018, respectively.

Nonemployee Director Fees Plan

The Company’s 2012 Nonemployee Director Fees Plan compensates nonemployee Directors for their board service with shares of common stock.  Directors were granted 5,875 and 6,625 shares for the three months ended March 30, 2019 and March 31, 2018, respectively. The Company recognized director stock compensation expense of $285 and $365 for the three months ended March 30, 2019 and March 31, 2018, respectively.