"It's an emotional product," Peterffy said of bitcoin on Monday. "It has no rhyme or reason for having the price that it has. But it could be, there's a small probability, it could become very popular."
Peterffy has said he's not opposed to trading the cryptocurrency, but he's been wary of linking it with the "real economy" through products such as futures.
In mid-November on CNBC's "Fast Money," he called CME's plans to launch bitcoin futures "suicidal" and said it "could bring down the entire economy." Peterffy even published a full-page advertisement in The Wall Street Journal that warned in an open letter to U.S. Commodity Futures Trading Commission Chairman J. Christopher Giancarlo of the dangers of clearing bitcoin on the same exchange as other established financial products. "For the first time, I am extremely scared," Peterffy told Barron's in a Nov. 11 article, citing worries about extreme volatility.
But his company took out a full-page ad this weekend in Investor's Business Daily promoting its bitcoin futures business. Interactive Brokers has also said its clients accounted for just over half of initial trading in the Cboe bitcoin futures contract, and is also allowing clients to trade the CME bitcoin futures.
A representative for Interactive Brokers said the company still has concerns about the clearing house structure for bitcoin futures and has imposed margin requirements far higher than that of Cboe and CME.
Peterffy is not the only financial markets business leader to tone down his stance on bitcoin in the last few months.
CME President Bryan Durkin said on Bloomberg Television in late September that bitcoin is "very nascent right now" and that "I really don't see us going forward with a futures contract in the very near future."
CME then announced on Oct. 31 that it planned to launch bitcoin futures by the end of the year.
The debut of bitcoin futures on the Cboe, and then the CME, was quite smooth. Cboe's bitcoin futures did trigger two trading halts on Dec. 10 as they surged in their launch, but CME's futures have yet to set off any trading halts due to volatility.
Bitcoin has come a long way in less than a decade from being the focus of a few tech nerds to a globally followed digital currency. More than 120 "cryptofunds" have launched this year to invest in cryptocurrencies, according to financial research firm Autonomous Next. The debut of bitcoin futures on established exchanges also allows institutional investors to buy into the cryptocurrency trend.