Since you bought 68.4246 BTC, you want to short 68 BTC and lock in the USD value. You will have 0.4246 BTC left over, which will give you a slightly long bias. You can either fix this by only buying 68 BTC in step 1 or by giving yourself more short exposure by shorting 69 BTC. Remember that CryptoFacilities contracts are inverse (which allow locking in USD) and are denominated in BTC
When cash markets are not functioning well, cash and carry arbitrage (and its reverse) futures markets may make the underlying asset accessible to more people. It is possible that A is bullish on bitcoin, but does not wish to go through the hassles of creating a wallet and storing it safely. At the same time, B might be comfortable with bitcoin wallets, but might be unwilling to take bitcoin price risk. Then B can buy bitcoin spot and sell cash settled bitcoin futures to A; the result is that A obtains exposure to bitcoin without creating a bitcoin wallet, while B obtains a risk free investment (a synthetic T-bill). Similarly, suppose C wishes to bet against bitcoin, but does not have the ability to short it; while D has no views on bitcoin, but has sufficient access to the cash market to be able to short bitcoin. Then D can take a risk free position by shorting bitcoin in the cash market and buying bitcoin futures from C who obtains a previously unavailable short position.
Individual shares of the Fund will be listed for trading on [the Exchange] and can be bought and sold in the secondary market at market prices. The market price of shares will fluctuate in response to changes in the value of the Fund’s holdings, supply and demand for shares, and other market factors. ProShare Advisors cannot predict whether the Fund’s shares will trade above, below or at a price equal to the value of the Fund’s holdings. Differences between secondary market prices and NAV, the value of the Fund’s holdings, may be due largely to supply and demand forces in the secondary market, which may not be the same forces as those influencing prices for securities or financial instruments held by the Fund at a particular time. Given the fact that the Fund’s shares can be created and redeemed in Creation Units, ProShare Advisors believes that large discounts or premiums to the value of the Fund’s holdings should not be sustained.
Institutional-tier offerings such as those detailed above are seen as much-needed catalysts to stimulate the flow of institutional money into the market, offering heavyweight financial players a less-risky way to buy into assets like bitcoin. For the same reason, custody services like those offered by Coinbase, BitGo and others are necessary for safely storing and managing these investments as well.
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.
There's a lot of ins and outs which can get confusing in arbitrage trading. We won't go into the technicals of why futures contracts trade at a premium to spot price. You can read a full explanation here. If it's not of interest to you, all you need to know is that there's a tendency, the further out in time the futures contract expires, for the premium to spot to be higher and higher in nominal percentage terms.