For hedging purposes, the Funds may invest in forward currency contracts to hedge either specific transactions (transaction hedging) or portfolio positions (position hedging). Transaction hedging is the purchase or sale of forward currency contracts with respect to specific receivables or payables of the Funds in connection with the purchase and sale of portfolio securities. Position hedging is the sale of a forward currency contract on a particular currency with respect to portfolio positions denominated or quoted in that currency.
One traditional attraction of trading futures is the ability to use relatively small amounts of money to potentially achieve outsized returns. In many futures markets the margin, the amount of money that your broker requires up-front before executing the trade can be quite small compared to the ultimate value of the contract. For example, as of 22-Dec-2017, each E-mini S&P 500 contract was worth $134K ($50*S&P 500 index value)—this “list price” of the contract is called its notional value.  The CME only requires you to maintain a minimum margin of $4.5K (3.4% of notional) to control this contract (brokers often require additional margin). Margin requirements this low are only possible because the volatility of the S&P 500 is well understood and your margin account balance is adjusted at the end of every trading day to account for the winnings or losses of the day. If your account balance falls below the margin minimum of $4.5K you’ll need to quickly add money to your account or your position will be summarily closed out by your broker. On the plus side, if you’ve predicted the S&P’s direction correctly your profits will be that same as if you completely owned the underlying stocks in the index. A +1% daily move in the S&P500 would yield $1340 in profit even though you only have $4500 invested— a 29% return—this multiplier effect is called leverage.
Market makers are challenged in fast markets—when either buyers or sellers are dominating and prices are moving rapidly. When this happens market makers are obligated to continue quoting bid and ask prices that maintain some semblance of an orderly market. If they start accumulating uncomfortably large net long or short inventories they may start hedging their positions to protect themselves. For example, if they are short Bitcoin futures they can buy Bitcoin futures with different expirations or directly buy Bitcoins to hedge their positions. The hedged portion of the market maker’s portfolio is not sensitive to Bitcoin price movements—their profit/losses on the short side are offset by their long positions.
Making money arbitraging bitcoin futures can be extremely simple. Futures contracts typically trade at a premium, and all you have to do, starting with USD, is buy bitcoin at Spot price and sell futures of the same amount at premium price. Then just wait until expiration to make your arb profit in bitcoin (which you can then put in USD). Whether it's a weekly, monthly, quarterly, or any futures contract, as long as it's in a premium, you lock in the sale price and earn the arbitrage profit.