Following yesterday’s big rally, the crypto market is cooling its heels a bit.

Total market capitalization for all cryptocurrencies peaked yesterday at around $263 billion. Today, that figure is down to about $247 billion—a drop of $16 billion in less than 24 hours.

That could be due to a selloff in altcoins in favor of Bitcoin, which is still trading today at close to $9,000 per coin.

Bitcoin gained around $1,000 to its price yesterday, surging 15% and rising all the way up to $9,400 before coming back down to $8,800 today.

The sudden surge in interest seemingly proved too much for some exchanges to handle. Trading came to a halt on Coinbase, which experienced prolonged technical difficulties just as Bitcoin was pumping. Coinbase said that as many as 61,000 Bitcoins—worth more than $500 million—were traded through its exchange on Wednesday.

But while Bitcoin trading has cooled a bit, altcoins have taken a more pronounced tumble. Ethereum is down close to 2%, trading at $211, while XRP has fallen more than 5%. Bitcoin, by comparison, is down less than 1%—and continues to track the stock market.

The S&P 500 likewise closed the day down less than 1%. The Dow Jones Industrial Average, meanwhile, dropped just over 1%, losing 300 points on the day. But, despite today’s slight dip, the stock market had its best month of trading in over 30 years.