At least $1 billion of customer funds have vanished from collapsed crypto exchange FTX, according to two people familiar with the matter.

The exchange’s founder Sam Bankman-Fried secretly transferred $10 billion of customer funds from FTX to Bankman-Fried’s trading company Alameda Research, the people told Reuters.

A large portion of that total has since disappeared, they said. One source put the missing amount at about $1.7 billion. The other said the gap was between $1 billion and $2 billion.

While it is known that FTX moved customer funds to Alameda, the missing funds are reported here for the first time.

The financial hole was revealed in records that Bankman-Fried shared with other senior executives last Sunday, according to the two sources. The records provided an up-to-date account of the situation at the time, they said. Both sources held senior FTX positions until this week and said they were briefed on the company’s finances by top staff.

Bahamas-based FTX filed for bankruptcy on Friday after a rush of customer withdrawals earlier this week. A rescue deal with rival exchange Binance fell through, precipitating crypto’s highest-profile collapse in recent years.

In text messages to Reuters, Bankman-Fried said he “disagreed with the characterization” of the $10 billion transfer.

“We didn’t secretly transfer,” he said. “We had confusing internal labeling and misread it,” he added, without elaborating.

Asked about the missing funds, Bankman-Fried responded: “???”

FTX and Alameda did not respond to requests for comment.