New York (CNN Business) The outspoken CEO of online home goods retailer Overstock.com resigned Thursday, days after he issued a press release entitled "Comments on Deep State" that claimed he helped the FBI carry out "political espionage."

The strange post from longtime Overstock chief Patrick Byrne triggered a steep decline in Overstock's stock price last week. The company's stock price later recovered, and it surged more than 10% Thursday on news of Byrne's exit.

In a letter Byrne issued Thursday, he stated that he is "already far too controversial to serve as CEO" and chose to step away after 20 years so that his presence wouldn't affect Overstock's business.

Byrne had said in an August 12 press release that he helped the FBI's "'Clinton Investigation' and the 'Russian Investigation'" — "operating under the belief that I was helping legitimate law enforcement efforts." He also claimed he "put the pieces" together in mid-2018 and realized the investigations amounted to "political espionage" against the 2016 US presidential candidates. Byrne said he decided to speak to journalists about his involvement this summer after discussing it with his rabbi.

"Coming forward publicly about my involvement in other matters was hardly my first choice," Byrne wrote in the letter about his resignation. "I now plan on leaving things to the esteemed Department of Justice (which I have doubtless already angered enough by going public) and disappearing for some time."

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