Assume it is January 3, 2015. Bob and Ann both want to trade at Bitcoin Futures Exchange (BFE). BFE offers 3 different contracts: one expiring and settling on Friday January 9 ('weekly'), another expiring Friday January 16th ('biweekly'), and finally one expiring in March 27 ('quarterly').  Each contract is worth 1 bitcoin notionally.  BFE has a policy that traders have to put 20% of margin down to enter a trade, so Bob and Ann deposit 0.2btc to their BFE accounts as they only want to trade 1 contract.
Bitcoin relies on blockchain technology. “Blockchain” is a decentralized database. Transactions are grouped in blocks and then chained together through cryptographic links. Blockchain is designed so that the chain can be added to, but not edited. This structure is called a “distributed ledger.” Transactions in the distributed ledger are permanently recorded and can never disappear, although theft and loss of bitcoin can occur. While bitcoin has grown in popularity, it’s still not nearly as widely accepted as traditional currency.
Anyone interested in buying bitcoins needs to deposit funds in U.S. dollars, euros, or another currency supported by the exchange. The popular methods of transferring money to the currency exchanges are through bank wire transfers, credit cards, or liberty reserves. One of the pre-requisites here is to have a digital wallet to hold bitcoins. Bitcoins bought can be stored in a digital wallet, device, or paper wallet, depending on the buyer’s preference. For sellers, the fait currency for which the Bitcoins have been sold needs to be withdrawn from the exchange and sent to a bank. One issue that can arise is if the exchange has liquidity concerns at a particular point in time; such situations can delay withdrawal and transfer of funds into a bank account. (For more, see: A Look At The Most Popular Bitcoin Exchanges.)
Commonly, investments subject to interest rate risk will decrease in value when interest rates rise and increase in value when interest rates decline. The value of securities with longer maturities may fluctuate more in response to interest rate changes than securities with shorter maturities. A wide variety of factors can cause interest rates to rise (e.g., central bank monetary policies, inflation rates, general economic conditions, etc.). This risk may be elevated under current economic conditions because interest rates are at historically low levels. Returns on investment in debt instruments may trail the returns on other investment options, including investments in equity securities.
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.