10 years ago, GoPro billionaire Nick Woodman made a promise to his college roommate, and it just cost him $229 million

Nick Woodman keeps his promises.

According to Bloomberg, the GoPro founder and CEO returned 4.7 million shares worth $229 million as part of an agreement he made with his college roommate 10 years ago.

Neil Dana, who attended the University of California at San Diego with Woodman, was GoPro's first employee.

He currently serves as the company's director of music and specialty sales.

When GoPro was in its early days, Woodman promised to give Dana 10% of any money he made from selling GoPro shares.

In 2011, GoPro issued Dana 6 million fully-vested options in addition to 270,000 restricted stock units, Bloomberg reports. Woodman said that he would reimburse GoPro when those options were exercised.

Dana spent $3.6 million to exercise his options this week. Woodman's net worth will fall to $2.3 billion after he returns the $229 million worth of shares to GoPro.