The Company has two shareholder–approved stock-based compensation plans. The 2006 Stock Incentive Plan was adopted in 2006 (“2006 Plan”) and had options granted under it through April 12, 2016. On June 1, 2016, the shareholders ratified the IAI 2016 Stock Incentive Plan (“2016 Plan”), which had been approved by the Board of Directors on April 4, 2016.

The Company recognizes compensation costs only for those shares expected to vest on a straight-line basis over the requisite service period of the awards. Such options generally vest over periods of six months to two years. There were no options granted in the three months ended March 31, 2019. Fair values of option awards granted in the three months ended March 31, 2018, were estimated using the Black-Sholes option pricing model under the following assumptions:

2016 Stock Incentive Plan

The 2016 Plan became effective June 1, 2016, and expires April 4, 2026. The 2016 Plan provides for the granting of equity awards to key employees, including officers and directors. The maximum number of shares for which equity awards may be granted under the 2016 Plan is 1,000,000. Options under the 2016 Plan expire no later than ten years from the date of grant or when employment ceases, whichever comes first, and vest over periods determined by the Board of Directors. The minimum exercise price of each option is the quoted market price of the Company’s stock on the date of grant. At March 31, 2019, there were unexpired options for 373,000 shares issued under the 2016 Plan, of which 332,000 were exercisable.

2006 Stock Incentive Plan

The 2006 Plan became effective May 18, 2006, and expired April 12, 2016. The 2006 Plan provides for the granting of equity awards to key employees, including officers and directors. Options under the 2006 Plan were generally granted at-the-money or above, expire no later than ten years from the date of grant or within three months of when employment ceases, whichever comes first, and vest over periods determined by the Board of Directors. The number of shares subject to options available for issuance under the 2006 Plan could not exceed 1,950,000. There were 999,000 unexpired options remaining from the 2006 Plan at March 31, 2019, of which 999,000 were exercisable.

The status of the options issued under the foregoing option plans as of March 31, 2019, and changes during the three months ended March 31, 2019, were as follows:

There were no options granted during the three months ended March 31, 2019. There were 130,000 options granted during the three months ended March 31, 2018, of which none were granted to non-employees. The weighted-average grant date fair values of options granted during the three months ended March 31, 2018, was $0.21. There were no options exercised during the three months ended March 31, 2019 and 2018. As of March 31, 2019, there was $3,079 of total unrecognized compensation cost related to non-vested share-based compensation arrangements granted under the stock incentive plans; that cost is expected to be recognized over a weighted-average period of six months.

Total compensation expense related to these plans was $4,454 and $6,288 for the three months ended March 31, 2019 and 2018, respectively, none of which related to options awarded to non-employees.

Nonvested option awards as of March 31, 2019 and changes during the three months ended March 31, 2019 were as follows: