Following its lackluster debut in the public markets, the brokerage based in Menlo Park, Calif., saw its stock steadily climb in the first trading days of August. Then, soon after the U.S. equity market opened for trading Wednesday, Robinhood shares, listed on Nasdaq under the ticker HOOD, exploded in value as related options contracts began to trade.

The stock quickly more than doubled its $38-a-share IPO price, reaching as high as $85—or more than 120% up from its debut. Shares spiked so high and so quickly that it managed to set off three separate trading halts from Nasdaq within 20 minutes of the market’s open. By the close of the market, Robinhood shares had slightly slid back to earth to $70.39, though still posting a staggering one-day climb of 50.41%.

HOOD’s rise has made the stock the talk of Wall Street less than a week after shares face-planted in their first day of trading, as weak investor interest unexpectedly awaited the company in the public markets. But now, with the stock’s spike, some like Interactive Brokers Chief Strategist Steve Sosnick are calling it the next GameStop or AMC Entertainment. “Robinhood has become the latest meme stock,” Sosnick told Fortune. “Speculative fervor is still alive and well.”

What changed Wednesday was the introduction of a financial instrument that Reddit’s WallStreetBetters and other day traders have long loved: options.

Options are contracts that allow the holder to either buy or sell the underlying security—in this case, Robinhood shares—in the future at a preset price. In total, Robinhood’s opening-day options volume reached almost 330,000 contracts, marking the second largest amount ever after Facebook, Cboe Head of Product Intelligence Henry Schwartz wrote in an Aug. 4 note. So-called put option contracts that will allow their holders to sell HOOD in the future slightly edged out the number of call contracts traded Wednesday by roughly 11,000.

The tricky world of options has become intermixed with the meme-stock bonanza of the last year, as such products helped fuel the run-up in GameStop shares where couch traders looked to squeeze hedge funds that shorted the stock. “One of the lessons learned by very aggressive traders participating at the height of the meme-stock era is that options can be utilized, if not weaponized, to get stonks moving,” Sosnick, a veteran options trader, said.

Robinhood’s options contracts began to trade at the same time that others on Wall Street gobbled up the stock itself. Cathie Wood, the prominent head of ARK Invest, has been loading up on Robinhood shares since its IPO. The ARK Fintech Innovation ETF added yet another 89,622 Robinhood shares Aug. 3, bringing its total position in the stock to 682,031 shares that had a market value of nearly $32 million. Wood’s ARK Innovation ETF holds another 4,891,168 shares of the stock with a market value of $228.9 million.

And now, the retail investors who have helped Robinhood become what it is today are piling in, too, even though sentiment on the stock remains mixed on platforms like Reddit’s WallStreetBets. A net $19.4 million worth of Robinhood shares were purchased Tuesday by retail investors, according to Vanda Research. That marked a 10-fold increase from the day before, the research shop said in an Aug. 4 report. However, Interactive Brokers’ Sosnick is quick to point out that the recent activity in Robinhood’s stock likely reaches well beyond retail. “It would be naive to think that it’s only retail,” Sosnick said. “I think you have a lot of institutions who have learned to game the retail trading and participate alongside it.”

Update Aug. 4, 2021: This article has been updated with further details of Robinhood’s stock performance.