CryptoFacilities, Coinpit, and BitMEX has a realtime profit realisation, while OKCoin and Deribit has weekly rebalancing scheduled for all contract lengths. It's important to note that on all of these exchanges, all the futures and forwards are non-deliverable and have expiration at various times. Despite this, OKCoin uses "delivery" as their term for expiration settlement of a contract, and "settlement" for the weekly rebalancing of the Pnl for higher length contracts. Since we are stuck with this unprofessional Chinese exchange being the dominant market player in futures, we have to focus on their use of the terminology, but BitMEX and CryptoFacilities have very impressive and professional setups that use well documented procedures. Always read the documentation of any exchange you're using and the contract specifications of the individual product you're using.
Source: MV Index Solutions GmbH (MVIS®). MVIS is a wholly owned subsidiary of Van Eck Associates Corporation. Data as of December 8, 2017 (synthesized data from BitMEX, OKCoin, CryptoFacilities, and BTCC which represents non-U.S. listed bitcoin futures trading on these exchanges). Not intended to be a forecast of future events, a guarantee of future results or investment advice. Current market conditions may not continue.  
Nothing contained herein is intended to be or to be construed as financial advice. Investors should discuss their individual circumstances with appropriate professionals before making any investment decisions. This information should not be construed as sales or marketing material or an offer or solicitation for the purchase or sale of any financial instrument, product or service.  
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Cryptocurrency is based on knowledge sharing on a distributed platform. The entire transactional history is for everyone to see. One blockchain is one thread of transaction. One unit or one block stores many transactions. The size of the block is 1MB and generally stores around 1000 to 2000 transactions. The data entered cannot be altered, nor can it be removed, enabling a system of complete transparency and trust. The entire money flow for the working model is beyond the traditional practices of controlling tax rates, credit usage, and money supply in the market.

Upon a sale, exchange or other disposition of shares of a Fund, a shareholder will generally realize a taxable gain or loss depending upon his or her basis in the shares. A gain or loss will be treated as capital gain or loss if the shares are capital assets in the shareholder’s hands, and generally will be long-term or short-term capital gain or loss depending upon the shareholder’s holding period for the shares. Any loss realized on a sale, exchange or other disposition will be disallowed to the extent the shares disposed of are replaced (including through reinvestment of dividends) within a period of 61 days beginning 30 days before and ending 30 days after the shares are disposed of. In such a case, the basis of the shares acquired will be adjusted to reflect the disallowed loss. Any loss realized by a shareholder on the disposition of a Fund’s Shares held by the shareholder for six months or less will be treated for tax purposes as a long-term capital loss to the extent of any distributions of Capital Gain Dividends received or treated as having been received by the shareholder with respect to such shares.
Crypto Facilities and the CME Group  have been calculating and publishing the Bitcoin Reference Rate (BRR) since November 2016. Such an official rate is a prerequisite of options trading in the traditional markets. The BRR is calculated based on the rates from the biggest exchanges: Bitstamp, GDAX, itBit, and Kraken. More concretely, it is calculated based on all Bitcoin vs. USD trades on the participating exchanges between 3 and 4 p.m. London time. To calculate the BRR, the hour between 3 and 4 is divided into 12 intervals of 5 minutes. For each interval, the volume-weighted median of the Bitcoin price is calculated (statistically, the median, in contrast to the average, prevents single outliers from distorting the price). The BRR is then the average of these 12 median values. More details about the calculation of the BRR can be found in the BRR whitepaper.

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.