Note 12. Warrants

On April 19, 2022, two warrants were exercised for a total of 500,000 shares of common stock resulting in the Company receiving $0.5 million.

On April 19, 2022, the holder of the 250,000 shares of Series C Preferred Stock received a warrant to purchase 25,000 shares of common stock at the price of $9.00 per share.

A summary of warrant activity for three months ended April 30, 2022 is as follows:

During the quarter ended April 30, 2022, stock based compensation expense related to warrant grants was $685,000, which consisted of grants to employees of $407,000, directors of $209,000, and consultants of $66,000. During the quarter ended April 30, 2021, there was no stock based compensation expense associated with warrant grants.