Synthetic prime brokerage
Prime brokerage done with derivatives. So instead of buying some shares on margin and asking your Template:Prime broker to hold them for you, you just trade a total return swap with your prime broker. The PB will buy the shares and hold in its own inventory.
You will be exposed to the price of the assets, but will not have any control or ownership. This can sometimes lead to disappointment when it comes to voting and corporate actions.