To illustrate the point, recall that futures markets are just counterparty contracts. Let's say I want to SHORT the market and profit off a decline in BTC/USD. If I put an order to sell Weekly futures contract at $400, and someone buys that offer, then we have created a futures contract. If it goes down, I profit and he loses, if it goes up, he profits and I lose. However, what if price goes down really fast, and my counterparty only had a little margin backing his position? Well, he gets margin-called when it goes down enough, and the system takes his contract and forces it to be sold to a different counterparty that wants to take the LONG side of my contract.

The Fund may invest in stocks of small- and mid- cap companies. The risk of equity investing may be particularly acute for securities of issuers with smaller market capitalizations. Small- and mid-cap company stocks may trade at greater spreads or lower trading volumes, and may be less liquid than the stocks of larger companies. Small- and mid-cap companies may have limited product lines or resources, may be dependent upon a particular market niche and may have greater fluctuations in price than the stocks of larger companies. Further, stocks of small- and mid-sized companies could be more difficult to liquidate during market downturns compared to larger, more widely traded companies. In addition, small- and mid-cap companies may lack the financial and personnel resources to handle economic or industry-wide setbacks and, as a result, such setbacks could have a greater effect on small- and mid- cap security prices.
This post-effective amendment relates only to ProShares Bitcoin Futures Strategy ETF, ProShares Short Bitcoin Futures Strategy ETF, ProShares Bitcoin Futures/Equity Strategy ETF and ProShares Bitcoin/Blockchain Strategy ETF, each a new series of ProShares Trust. No information relating to any other series or class of series of ProShares Trust is amended or superseded hereby.
In the course of managing the Fund’s investments, ProShare Advisors will need to periodically adjust the Fund’s holdings in order to maintain investment exposure approximately equivalent to the Fund’s assets. This process entails obtaining additional inverse exposure as the Fund experiences gains, and reducing inverse exposure as the Fund experiences losses. The higher the volatility of the bitcoin futures contracts in which the Fund invests, the more such rebalancing can adversely affect the Fund’s performance.
The exceptions to withholding for Capital Gain Dividends and short-term capital gain dividends do not apply to (A) distributions to an individual foreign shareholder who is present in the United States for a period or periods aggregating 183 days or more during the year of the distribution and (B) distributions attributable to gain that is treated as effectively connected with the conduct by the foreign shareholder of a trade or business within the United States under special rules regarding the disposition of U.S. real property interests as described below. The exception to withholding for interest-related dividends does not apply to distributions to a foreign shareholder (A) that has not provided a satisfactory statement that the beneficial owner is not a U.S. person, (B) to the extent that the dividend is attributable to certain interest on an obligation if the foreign shareholder is the issuer or is a 10% shareholder of the issuer, (C) that is within certain foreign countries that have inadequate information exchange with the United States, or (D) to the extent the dividend is attributable to interest paid by a person that is a related person of the foreign shareholder and the foreign shareholder is a controlled foreign corporation. If a Fund invests in a RIC that pays Capital Gain Dividends, short-term capital gain dividends or interest-related dividends to the Fund, such distributions retain their character as not subject to withholding if properly reported when paid by the Fund to foreign shareholders. A Fund is permitted to report such part of its dividends as interest-related and/or short-term capital gain dividends as are eligible, but is not required to do so.
Investment income and gains received by a Fund from foreign investments may be subject to foreign withholding and other taxes, which could decrease the Fund’s return on those investments. The effective rate of foreign taxes to which a Fund will be subject depends on the specific countries in which its assets will be invested and the extent of the assets invested in each such country and, therefore, cannot be determined in advance. If more than 50% of a Fund’s assets at year end consists of the securities of foreign corporations, the Fund may elect to permit shareholders to claim a credit or deduction on their income tax returns for their pro rata portions of qualified taxes paid by the Fund to foreign countries in respect of foreign securities that the Fund has held for at least the minimum period specified in the Code. In such a case, shareholders will include in gross income from foreign sources their pro rata shares of such taxes paid by the Fund. A shareholder’s ability to claim an offsetting foreign tax credit or deduction in respect of foreign taxes paid by the Fund is subject to certain limitations imposed by the Code, which may result in the shareholder’s not receiving a full credit or deduction (if any) for the amount of such taxes. Shareholders who do not itemize on their U.S. federal income tax returns may claim a credit (but not a deduction) for such foreign taxes. Even if a Fund were eligible to make such an election for a given year, it may determine not to do so. Shareholders that are not subject to U.S. federal income tax, and those who invest in a Fund through tax-advantaged accounts (including those who invest through individual retirement accounts or other tax-advantaged retirement plans), generally will receive no benefit from any tax credit or deduction passed through by the Fund.
On May 7, 2014, the SEC published an investor alert that highlighted fraud and other concerns relating to certain investment opportunities denominated in bitcoin and fraudulent and unregistered investment schemes targeted at participants in online bitcoin forums. On July 25, 2017, the SEC issued a Report of Investigation or Report which concluded that digital assets or tokens issued for the purpose of raising funds may be securities within the meaning of the federal securities laws. The Report emphasized that whether a digital asset is a security is based on the particular facts and circumstances, including the economic realities of the transactions. This was reiterated in a December 11, 2017 Public Statement emphasizing the risks of investing in digital assets such as bitcoin and noting the possibility that bitcoin and other digital assets may be deemed to be securities. The SEC continues to take action against persons or entities misusing bitcoin in connection with fraudulent schemes (i.e., Ponzi scheme), inaccurate and inadequate publicly disseminated information, and the offering of unregistered securities.
The policy for each Fund regarding purchases and sales of securities is that primary consideration will be given to obtaining the most favorable prices and efficient executions of transactions. Consistent with this policy, when securities transactions are effected on a stock exchange, the policy is to pay commissions that are considered fair and reasonable without necessarily determining that the lowest possible commissions are paid in all circumstances. The Advisor believes that a requirement always to seek the lowest possible commission cost could impede effective portfolio management and preclude the Fund and the Advisor from obtaining a high quality of brokerage and execution services. In seeking to determine the reasonableness of brokerage commissions paid in any transaction, the Advisor relies upon its experience and knowledge regarding commissions generally charged by various brokers and on its judgment in evaluating the brokerage and execution services received from the broker. Such determinations are necessarily subjective and imprecise, as in most cases an exact dollar value for those services is not ascertainable. In addition to commission rates, when selecting a broker for a particular transaction, the Advisor considers but is not limited to the following efficiency factors: the broker’s availability, willingness to commit capital, reputation and integrity, facilities reliability, access to research, execution capacity and responsiveness.
The NAV per share of each Fund is computed by dividing the value of the net assets of such Fund (i.e., the value of its total assets less total liabilities) by its total number of Fund shares outstanding. Expenses and fees are accrued daily and taken into account for purposes of determining NAV. The NAV of each Fund is calculated by JPMorgan Chase Bank, National Association. The NAV of each Fund is generally determined each business day at the close of regular trading of the                    (ordinarily 3:00 p.m. Eastern time). The Fund’s investments are generally valued at their market value using information provided by a pricing service or market quotations. Short-term securities are valued on the basis of amortized cost or based on market prices. In addition, routine valuation of certain other derivatives is performed using procedures approved by the Board.
Bob's transaction confirms first so he goes on BFE and looks at the contract selections. He wants to trade on the January 9 expiration contract. The orderbook is empty and Bob wants to go long (profit off an increase in bitcoin). Since there are no offers available, he places a limit order in the orderbook for a bid at 400 of 1 contract, using his 0.2btc as collateral for the position.
The investment restrictions of the Funds specifically identified as fundamental policies may not be changed without the affirmative vote of at least a majority of the outstanding voting securities of that Fund, as defined in the 1940 Act. The investment objectives and all other investment policies of the Funds not specified as fundamental (including the index of a Fund) may be changed by the Board without the approval of shareholders.

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.