Some of Larry Ellison's emails with his financial advisor became public and talk about doing just this.

It is common practice for nearly all those wealthy people relying on stocks. What I am interested in is the interest rate they get on those loans.

It's actually lower than retail bank interest rates. For example, if they get a huge mortgage, usually it is at least 100 basis points lower. This is because these people are considered extremely low risk.

I have heard it is pretty common for them to get 1 or 2% because the banks usually want to win their business.