The founder and CEO of the online retailer Overstock.com, Patrick Byrne, announced Thursday that he would resign effective immediately. Byrne had become embroiled in controversy after making wild claims of being involved in the federal government’s probe into Russian interference in the 2016 presidential election. He called FBI agents “the Men in Black” and said the investigation was “less about law enforcement and more about political espionage conducted against Hillary Clinton and Donald Trump.” He also had cultivated a three-year romantic relationship with the Russian agent Maria Butina, who is now serving an 18-month prison sentence after being accused of attempting to infiltrate the U.S. government on behalf of her country. Byrne had worked as CEO for more than 20 years, taking Overstock from startup to large public company.

Overstock shares rose 17 percent on the news of his departure, according to CNBC. The stock previously fell more than 30 percent in response to Byrne’s remarks. The company appointed an interim CEO in Byrne’s place, CNBC reported.