Yes, but if the market goes south 20% the way it did just recently in 2020, they call you up and ask you to put in $5M more or they will liquidate everything that day. So it's not risk free.

I work in levered hedge fund strategies, so I have some insight here, although I don't negotiate financing myself. Banks tailor leverage to your strategy, so if your strategy is just to go long good stocks you won't get anything like 6X leverage. 6X leverage is realistic for a strategy that is long and short equal dollar amounts, and also carefully controls other risks besides dollar exposures.

Also, you have to be fairly big to get that kind of leverage. $100 million is probably too small but $1B might be enough.

So you put up $1B of your own money, and a bank would let you go long $3B and short $3B. The idea is that your longs hedge your shorts well so you can't lose too much.

Obviously, in the case of Archegos the shorts didn't hedge the longs well.

You can get up to 12 to 1 leverage with 5+ million dollars account with most brokerage firms, but it will be substantially depended on your reputation as manager, fees you willing to pay and most importantly your market exposure. Assuming regulations did not change since 2014 or so.

Yeah it's possible, but it makes more sense to think about negative outcomes before positive outcomes. With enough leverage, you lose half of your money if the market goes down 10%. With more leverage, you lose all your money if the market goes down a few percentage points, as your account gets liquidated on the spot.

If you want to understand, the search terms are ‘portfolio margin’ (equities and equity/index options) and ‘SPAN margin’ (futures and futures options)