Sam Bankman-Fried’s trading firm Alameda Research reportedly owes his crypto exchange FTX $10 billion after taking loans funded by deposits from FTX customers, according to The Wall Street Journal.

As economist Frances Coppola pointed out to the Journal, exchanges like FTX shouldn’t be investing customers’ money. “It shouldn’t be doing anything with those assets. They should literally be sitting there so people can use them,” said Coppola. That’s especially true for volatile markets like crypto, where collateral could swing in value from one day to the next.

However, FTX reportedly lent over half of its customer funds to Alameda, which then used them to bet on other cryptocurrencies and help out other crypto firms struggling to weather an overall downturn in the market.