On October 31, 2017, CME Group, the world's leading and most diverse derivatives marketplace, had announced its intent to launch bitcoin futures in the fourth quarter of 2017. “CME Group's Bitcoin futures will be available for trading on the CME Globex electronic trading platform, and for submission for clearing via CME ClearPort, effective on Sunday, December 17, 2017 for a trade date of December 18” as per CME’s officials statement.
The value of such Creation Unit for the Equities for Rising Rates ETF, the S&P MidCap 400 Dividend Aristocrats ETF, the Russell 2000 Dividend Growers ETF, the MSCI Emerging Markets Dividend Growers ETF, the Managed Futures Strategy ETF, the Crude Oil Strategy ETF, the UltraPro Short Nasdaq Biotechnology ETF, the Short 7-10 Year Treasury ETF and the Ultra Gold Miners ETF as of each Fund’s inception was $1,000,000.
A cryptocurrency (or crypto currency) is a digital asset designed to work as a medium of exchange that uses strong cryptography to secure financial transactions, control the creation of additional units, and verify the transfer of assets.[1][2][3] Cryptocurrencies are a kind of alternative currency and digital currency (of which virtual currency is a subset). Cryptocurrencies use decentralized control[4] as opposed to centralized digital currency and central banking systems.[5] The decentralized control of each cryptocurrency works through distributed ledger technology, typically a blockchain, that serves as a public financial transaction database.[6][7]
The right of redemption may be suspended or the date of payment postponed with respect to any Fund (1) for any period during which the Exchange is closed (other than customary weekend and holiday closings); (2) for any period during which trading on the Exchange is suspended or restricted; (3) for any period during which an emergency exists as a result of which disposal of the shares of the Fund’s portfolio securities or determination of its NAV is not reasonably practicable; (4) in such other circumstance as is permitted by the SEC; or (5) for up to 14 calendar days for any of the Global Funds or Short or Ultra International ProShares Funds during an international local holiday, as described below in “Other Information”.

With BitVC and OKCoin you can hold simultaneous long and short positions on the same contract. In BitMEX you can not. Technically it makes no sense to hold opposite simultaneous positions because it just cancels each other out. You may as well just close the position instead. There are some who still prefer, for psychological reasons, to use this and wrongly call it a "hedge", but really you're better off saving the trading fees and just getting out of a position if your outlook on a trade has changed.

Don’t be greedy. No one ever lost money taking a profit. As a coin begins to grow, the greed inside us grows along with it. If a coin increases by 30%, why not consider taking profit? Even if goals are set to 40% or 50%, you should at least pull out some of the profit on the way up in case a coin doesn’t reach the goal. If you wait too long or try to get out at a higher point, you risk losing profit you already earned or even turning that profit into a loss. Get into the habit of taking profits and scouting for re-entry if you want to continue reaping potential profits.

Each Fund, except for S&P 500 Dividend Aristocrats ETF, S&P MidCap 400 Dividend Aristocrats ETF, Russell 2000 Dividend Growers ETF, MSCI EAFE Dividend Growers ETF, MSCI Europe Dividend Growers ETF, MSCI Emerging Markets Dividend Growers ETF, Morningstar Alternatives Solution ETF, Long Online/Short Stores, DJ Brookfield Global Infrastructure ETF, Global Listed Private Equity ETF, Large Cap Core Plus, S&P 500 Ex-Energy ETF, S&P 500 Ex-Financials ETF, S&P 500 Ex-Health Care ETF, S&P 500 Ex-Technology ETF, Equities for Rising Rates ETF, High Yield—Interest Rate Hedged, Investment Grade—Interest Rate Hedged, Short Term USD Emerging Markets Bond ETF, Hedge Replication ETF, Merger ETF, RAFI® Long/Short, and Inflation Expectations ETF (each, a “Matching ProShares Fund” and collectively, the “Matching ProShares Funds” or “Matching Funds”), Managed Futures Strategy ETF, Crude Oil Strategy ETF, CDS Short North American HY Credit ETF, Bitcoin Futures Strategy ETF, Blockchain/Bitcoin Strategy ETF, Bitcoin Futures/Equity Strategy ETF, and Short Bitcoin Futures Strategy ETF is “Geared” in the sense that each is designed to seek daily investment results, before fees and expenses, that correspond to the performance of a daily benchmark such as the inverse (-1x), multiple (i.e., 2x or 3x), or inverse multiple (i.e., -2x or -3x) of the daily performance of an index for a single day, not for any other period (for purposes of this SAI, the term “index” includes
The CFTC, in conjunction with other federal regulators, also recently proposed stricter margin requirements for certain swap transactions. If adopted, the proposed requirements could increase the amount of margin necessary to conduct many swap transactions, limit the types of assets that can be used as collateral for such transactions, and impose other restrictions. The rule proposal may affect the ability of the Funds to use swap agreements (as well as futures contracts and options on futures contracts or commodities) and may substantially increase regulatory compliance costs for the Advisor and the Funds. As of the date of this SAI, the ultimate impact of the rule proposal on the Funds is uncertain. It is possible, however, that any adopted rule may adversely affect the Advisor’s ability to manage the Funds, may impair a Funds’ ability to achieve its investment objective and/or may result in reduced returns to Fund investors.

A U.S. person, including a Fund, who owns (directly or indirectly) 10% or more of the total combined voting power of all classes of stock of a foreign corporation is a “U.S. Shareholder” for purposes of the CFC provisions of the Code. A CFC is a foreign corporation that, on any day of its taxable year, is owned (directly, indirectly, or constructively) more than 50% (measured by voting power or value) by U.S. Shareholders. Because of its investment in its Subsidiary, each Parent Fund is a U.S. Shareholder in a CFC. As a U.S. Shareholder, each Parent Fund is required to include in gross income for U.S. federal income tax purposes for each taxable year of the Fund its pro rata share of its CFC’s “subpart F income” for the CFC’s taxable year ending within the Fund’s taxable year whether or not such income is actually distributed by the CFC, provided that the foreign corporation has been a CFC for at least 30 uninterrupted days in its taxable year. Subpart F income generally includes interest, OID, dividends, net gains from the disposition of stocks or securities, net gains from transactions (including futures, forward, and similar transactions) in commodities, receipts with respect to securities loans, and net payments received with respect to equity swaps and similar derivatives. Subpart F income is treated as ordinary income, regardless of the character of the CFC’s underlying income. Net losses incurred by a CFC during a tax year do not flow through to an investing Fund and thus will not be available to offset income or capital gain generated from that Fund’s other investments. In addition, net losses incurred by a CFC during a tax year generally cannot be carried forward by the CFC to offset gains realized by it in subsequent taxable years. To the extent each Parent Fund invests in its Subsidiary and recognizes subpart F income in excess of actual cash distributions from such the Subsidiary, if any, it may be required to sell assets (including when it is not advantageous to do so) to generate the cash necessary to distribute as dividends to its shareholders all of its income and gains and therefore to eliminate any tax liability at the Fund level. Subpart F income also includes the excess of gains over losses from transactions (including futures, forward and other similar transactions) in commodities.

The CME considers a hard fork of the Bitcoin Blockchain where both forks continue to be actively mined and traded but may not be fungible with each other, as an unusual and extreme circumstance. As such, CME provides that Crypto Facilities Ltd. (CME’s administrator) shall be responsible for recommending the necessary actions and responses to ensure the relevance and integrity of the Bitcoin Pricing Products.

•   Futures Position Limit Risk — Limits on the amount of futures any one entity can hold may negatively impact the Fund’s ability to meet its investment objective if such limits are reached and exceptions to such limits are not granted. Currently the position limits for bitcoin futures contracts are much lower than they are for most other futures contracts.

Various government agencies, departments, and courts have classified bitcoin differently. China Central Bank banned the handling of bitcoins by financial institutions in China in early 2014.[69] In Russia, though cryptocurrencies are legal, it is illegal to actually purchase goods with any currency other than the Russian ruble.[70] Regulations and bans that apply to bitcoin probably extend to similar cryptocurrency systems.[71]
The Funds may invest in equity securities. The market price of securities owned by a Fund may go up or down, sometimes rapidly or unpredictably. Securities may decline in value due to factors affecting securities markets generally or particular industries represented in the securities markets. The value of a security may decline due to general market conditions not specifically related to a particular company, such as real or perceived adverse economic conditions, changes in the general outlook for corporate earnings, changes in interest or currency rates, or adverse investor sentiment generally. A security’s value may also decline due to factors that affect a particular industry or industries, such as labor shortages or increased production costs and competitive conditions within an industry. The value of a security may also decline for a number of reasons that directly relate to the issuer, such as management performance, financial leverage and reduced demand for the issuer’s goods or services. Equity securities generally have greater price volatility than fixed income securities, and the Funds are particularly sensitive to these market risks.
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