Stocks gained in the past week on optimism for a $1.9 trillion stimulus package, proposed by President Joe Biden. But by Friday, the market lost steam amid increased concerns about the pandemic’s economic impact, and as it seemed Biden would not have an easy time getting the stimulus plan approved.

Stimulus euphoria may be waning, but investors will have plenty to focus on in the week ahead, as a blast of earnings news hits, the Federal Reserve meets and new data will show the state of the economy at the end of the year.

Matt Maley, chief market strategist at Miller Tabak, said a pullback could be sparked if bitcoin starts to fall more sharply, since some investors would sell stock in response. “When there’s no bid in bitcoin they have to sell something, and they sell stock,” said Maley.

Bitcoin has had a wild early ride in 2021. The cryptocurrency hit a record high of $41,973 on Jan. 12, according to data from Coin Metrics. Days later, it fell about 15%, wiping out as much as $200 billion in just 24 hours.

Bitcoin then regained some of its losses, surging to near $40,000 before another reversal. On Friday, it was trading at $33,200 after dipping below $30,000.

“If this thing starts tanking again, it’s going to cause some forced selling and it’s going to cause some selling in the stock market,” said Maley, adding it will be important to hold the low from Thursday night.

He said the short position in the dollar is also an overcrowded trade that could turn quickly. A resulting short squeeze could cause a dollar rally that would be negative for the stock market. He also is watching Tesla, which reports earnings on Wednesday.

“I think whether it be bitcoin, the dollar, Tesla, one of these crowded trades…it’s going to turn the narrative that’s permeating right now, and if we don’t get a surprise the market will continue to push higher,” he said.