The head of a small biotech company-turned-crypto has made hundreds of thousands of dollars in stock sales already.

John O'Rourke, president, CEO and chairman of Riot Blockchain, disclosed in a Friday filing with the U.S. Securities and Exchange Commission that he sold 30,383 shares at a weighted average price of about $28.61 a share.

That means O'Rourke received a gross payout of $869,256 and made at least $712,000 on Riot's 600-plus percent price surge in the last few months on a name change that added the word "blockchain."

Announcements tying companies to the blockchain technology that also backs bitcoin have caused several tiny stocks to soar dramatically in the last several months. In December, bitcoin itself had briefly surged about 1,900 percent for the year.

Riot Blockchain was once primarily a biotech company named Bioptix. In early October, the company announced it was changing its name to focus on blockchain-related investments, and shares soared. The company also changed its ticker symbol to RIOT from BIOP.

The stock climbed 648 percent from $5.16 at the end of September to a closing high of $38.60 on Dec. 19. As a result, the company's market value jumped from around $17 million this past summer to near $270 million in December, according to FactSet.