Wang was told to create a "backdoor, a secret way for Alameda to borrow from customers on the exchange without permission," said FTX lawyer Andrew Dietderich.

"Mr. Wang created this back door by inserting a single number into millions of lines of code for the exchange, creating a line of credit from FTX to Alameda, to which customers did not consent," he added. "And we know the size of that line of credit. It was $65 billion."

The Commodity Futures Trading Commission (CFTC) made similar allegations when it brought charges against Wang in December. But the value of that line of credit hasn't been discussed before now. The CFTC then described it as "virtually unlimited."

And in November, Reuters cited unnamed sources as saying that Bankman-Fried had moved $10 billion between the two companies, with a further $2 billion still unaccounted for. 

Dietderich told the court that with the $65 billion back door, Alameda "bought planes, houses, threw parties, made political donations."

Bankman-Fried is the second-highest donor to Democratic causes, but says he donated just as much to Republicans using "dark" money.