Also not my experience. Accidentally had a timing issue once, and was overdrawn for a week before an ACH more than covered the difference.

On day four they called me to make sure I was aware. I explained that I had already started a transfer several days earlier, and they said "no problem" and thanked me for being a customer.

No overdraft fees, no pulling from my brokerage account, no margin loan. Never heard anything about it ever again.