Unfortunately, I don't have a reference, as I was told this by an advisor from PWC a few years ago. I guess you could contact any good tax consultant, tell him the details, and let him look into it. I have no idea about how 401K works in the US.
Real estate is the only asset class where you can very easily get 10-20x leverage, and at rates that are only modestly above the risk free rate.
If you used $1,000,000 to buy $20,000,000 worth of property in San Francisco, and you wanted to get a 15% annual return to beat the market, the numbers would look like this:
You’d be paying around $600,000 in interest, say you’ve got another $100,000 in expenses, and you want to get $150,000 for your return. That’s $850,000 that needs to come from somewhere, in San Francisco I think the rent to price ratio is about 1:50, so that’s $400,000 in rent, and the remaining $450,000 needs to come from house prices increasing. So to beat the market your property assets needs to appreciate by 2.25%, or about what the fed targets inflation to be.
This is only possible because the mortgage is a very unique debt instrument. As far as access to cheap debt goes, it is comparable only to the highest credit corporate and sovereign bonds. The only type of debt that a regular consumer has access to, that is somewhat comparable, are subsides student loans.
