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. Fair values of option awards granted in the three months and six months ended June 30, 2021 and 2020, were estimated using the Black-Scholes option pricing model under the following assumptions:

Given the limited public market for the Company’s stock, the Company has elected to estimate its expected volatility by benchmarking its volatility against the calculated volatility of several public company issuers that operate within its market segment. The first issuance for which this benchmarking was applied was effective with options granted on March 31, 2021.

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 within prescribed periods following cessation of employment, 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 June 30, 2021, there were unexpired options for 828,500 shares issued under the 2016 Plan, of which 346,000 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 within prescribed periods following cessation of employment, 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 434,000 unexpired options remaining from the 2006 Plan at June 30, 2021, all of which were exercisable.

The status of the options issued under the foregoing option plans as of June 30, 2021 and 2020, and changes during the three months and six months ended June 30, 2021 and 2020, were as follows:

There were 127,500 options and 10,000 options granted during the three months ended June 30, 2021 and 2020, respectively, and there were 272,500 options and 10,000 options granted during the six months ended June 30, 2021 and 2020, respectively. There were 360,000 options and no options exercised during the three months ended June 30, 2021 and 2020, respectively, and there were 385,000 options and no options exercised during the six months ended June 30, 2021 and 2020, respectively. As of June 30, 2021, there was $210,230 of total unrecognized compensation cost related to nonvested share-based compensation arrangements granted under the stock incentive plans; that cost is expected to be recognized over a weighted-average period of five months.

Total compensation expense related to these plans was $111,862 and $356 for the three months ended June 30, 2021 and 2020, respectively, and $139,573 and $806 for the six months ended June 30, 2021 and 2020, respectively.

Nonvested option awards as of June 30, 2021 and 2020, and changes during the three months and six months ended June 30, 2021 and 2020, were as follows: