Wall Street eyes a possible culprit in this week’s head-spinning stock market reversal: Bitcoin

Nvidia’s blockbuster earnings late Wednesday set up the stock market for a ferocious rebound as the chipmaker appeared to ease fears that an AI bubble was about to pop.

Thursday began with a massive rally with the Dow Jones Industrial Average up 700 points, regaining some ground after an earlier AI-related selloff. Upbeat results from retail giant Walmart helped too.

But the market suddenly turned lower, and the Dow lost 300 points, leaving Wall Street wondering what the heck happened.

Some commentators pointed to persistent worries about an AI bust, while others cited the mixed September jobs report that showed strong payroll gains but an uptick in the unemployment rate to the highest level in four years.

Meanwhile, Federal Reserve policymakers have been sounding increasingly hawkish, putting a rate cut next month in doubt.

Market veteran Ed Yardeni, cited these factors in a note late Thursday along with the selloff in the world’s leading cryptocurrency.

“We attribute some of today’s stock market selloff to the ongoing plunge in bitcoin’s price,” he wrote. “There has been a strong correlation between it and the price of TQQQ, an ETF that seeks to achieve daily investment results that correspond to three times (3x) the daily performance of the Nasdaq-100 Index.”

Yardeni blamed bitcoin’s slide on the GENIUS Act, which was enacted on July 18, saying that the regulatory framework it established for stablecoins eliminated bitcoin’s transactional role in the monetary system.

“It’s possible that the rout in bitcoin is forcing some investors to sell stocks that they own,” he added.

Bitcoin has tumbled more than 30% from earlier highs, suffering its worst slump since 2022. Traders who used leverage to make crypto bets would need to liquidate positions in the event of margin calls.

Steve Sosnick, chief strategist at Interactive Brokers, also said bitcoin could swing the entire stock market, pointing out that it’s become a proxy for speculation.

“As a long-time systematic trader, it tells me that algorithms are acting upon the relationship between stocks and bitcoin,” he wrote in a note on Thursday. “Traders have always sought to find relationships between asset classes, and there are teams of skilled quants who pore through data, both long- and short-term, seeking inputs that guide their decisions. We called them ‘leads.’”

And in recent days, Sosnick added, bitcoin has become one of the most reliable leads.

Tom Lee, Fundstrat Global Advisors’ head of research, linked crypto with the AI trade in particular, noting that investors with big holdings in AI-related stocks also tend to own bitcoin.

“I think crypto, bitcoin and ethereum are in some ways a leading indicator for equities because of that unwind and now this sort of limping and weakened liquidity,” he told CNBC on Thursday.

This story was originally featured on Fortune.com