What you're asking, in typical futures terminology(1), is how the futures market can function if futures positions and spot/physical positions are not cross-mar

What you're asking, in typical futures terminology(1), is how the futures market can function if futures positions and spot/physical positions are not cross-margined. This is actually typical in commodities futures. The same issues apply to crude oil and corn futures (physical settlement) and live hog futures (financial settlement). So how does the market function? If you're in the business of cash and carry arbitrage, either you have a lot of money, or you borrow it. At scale these types of strategies require a lot of capital to purchase the spot side, so a relationship with a lender is important even without the margin. The lender knows about both sides of the trade, so you can generally get good terms. And your margin balance pays interest, so the extra borrowing to cover the margin doesn't cost you that much. It is a real cost of doing business though, which is why margins are generally so low/allowed leverage is so high in futures world compared to securities. Should be interesting to see how they margin the bitcoin futures, because bitcoins are an order of magnitude more volatile than most other products. (1) The money you post to a futures clearing firm to guarantee against default is called either margin or a performance bond. Same concept as collateral, but the word collateral is usually only used in the context of guaranteeing payment of a debt.