my father has been in the real estate investment business for like 25+ years.
i dont understand it all, but sort of like this:
his company would evaluate a multi-million dollar property, find it's worth, and approve or deny the loan, and administer the loan, including the escrow.
the billions were not "his" to loan, but from an institution, the last one was JP morgan. morgan used an option to buy, in a hostile move, and bought my father's business that did that a few years ago.
most recently he worked for a subsidary of GMAC, until the fall in NYC and head injury made it not possible for him to work fully (no flying, and limited work hours)
his last biggest deal was the re-finance of the world trade center about a month before 9/11