According to a report published by Nansen, FTX and Alameda have had close (on-chain) ties since the very beginning.

FTX created FTX Token (FTT), a token for their platform, involving Alameda since day one. The two of them shared the majority of the total FTT supply which did not really enter into circulation.

The initial success of Alameda, FTX, and the meteoric rise of FTT most likely led to a rise in the value of Alameda’s balance sheet. This high balance sheet value of the FTT positions was likely used as collateral by Alameda to borrow against. If the borrowed funds were used to make illiquid investments, FTT would become a central weakness for Alameda.

With the collapse of Terra/UST in May, a liquidity crunch ensued as many creditors started to call back loans following the 3AC and Celsius crashes. Alameda would have needed liquidity from a source that would still be willing to give out a loan against their existing collateral

Alameda deposited around ~$3b worth of FTT on FTX of which most remained there until the end.