That's right. Deposited and then w/t to wherever he keeps investment accounts. I'm fairly certain that it's not even possible to deposit third party checks into brokerage accounts. They want the funds to be originated from a bank account in the account holder's name.
As James L said...temporary holding of funds and then swept into some interest bearing or brokerage account.
If it is 3rd party funds, then you have to ask why is anyone tapping the funds for personal use? If business related expenses, then you use checks, not cash. Co-mingling of personal and corporate/investor funds is a major no-no.
guy could have $5B liquid and it would be 2% of his net worth. IIRC the guys at dealbreaker actually saw the ATM receipt. Many banks have very low ATM w/d limits.