[prostoalex]

For clients of that size it's most likely a variant of a pledged asset line http://www.schwab.com/public/schwab/banking_lending/pledged_... at some subsidized rate in order to win their wealth management and private banking business. I mean, if you have significant holdings and if you're okay with borrowing on a floating rate, and if you think you can survive a margin call, Interactive Brokers will lend to you at 0.86% if you park $1m+ of securities with them. https://www.interactivebrokers.com/en/?f=interest You'd be hard-pressed to find a mortgage on similar terms.

It's a mortgage in layman's terms as there's some principal and interest, but in reality the financial institution won't send an appraiser, there's no mortgage deed issued to the bank, the balance and interest payments are not sliced and diced into securities to be resold.

With that said, mortgages for LLCs are the preferred financing instruments for real estate investors, so they're actually a significant line of business for some banks and yes, they're very doable.