An unidentified man held up a sign saying "buy bitcoin" during Fed Chair Janet Yellen's testimony Wednesday before the House Financial Services Committee.

subsequently climbed toward session highs and traded 3.7 percent higher, at $2,418.46, as of 2:27 p.m. ET, according to CoinDesk.

The unidentified bitcoin proponent, whose stunt was visible on television, was removed from the hearing room. Holding up the sign violates the House committee's rules. Committee staffers told CNBC they didn't know the man's name.

Bitcoin doesn't need the free advertising. The digital currency has more than doubled in value this year, raising concerns it is entering bubble territory.

Yellen was speaking during the first round of the Fed's semiannual monetary policy report to Congress and the state of the economy.

Fundstrat's Tom Lee said in a note Friday that central banks may one day buy digital currencies like bitcoin. Lee was the first major Wall Street strategist to issue a report on the cryptocurrency.

Yellen did not comment on cryptocurrency during her testimony.

— CNBC's Matt Cuddy contributed to this report.