Let’s say Larry owns one bitcoin and the current price is $16,600, be believes the price is overdone to the upside for a short period of time.  This is a fictional example, so don’t beat me up on the outlook, you can criticize Larry, but he’s made up too.  Larry has a futures account and sees that he can sell short a January XBT Future at $17,600.  He decides to do this and is now short 1 January XBT Future at $17,600. 
CCC – An obligation rated ‘CCC’ is currently vulnerable to nonpayment, and is dependent upon favorable business, financial, and economic conditions for the obligor to meet its financial commitment on the obligation. In the event of adverse business, financial, or economic conditions, the obligor is not likely to have the capacity to meet its financial commitment on the obligation.
The Funds may invest in foreign issuers, securities traded principally in securities markets outside the United States, U.S.-traded securities of foreign issuers and/or securities denominated in foreign currencies (together “foreign securities”). Also, each Fund may seek exposure to foreign securities by investing in Depositary Receipts (discussed below). Foreign securities may involve special risks due to foreign economic, political and legal developments, including unfavorable changes in currency exchange rates, exchange control regulation (including currency blockage), expropriation or nationalization of assets, confiscatory taxation, taxation of income earned in foreign nations, withholding of portions of interest and dividends in certain countries and the possible difficulty of obtaining and enforcing judgments against foreign entities. Default in foreign government securities, political or social instability or diplomatic developments could affect investments in securities of issuers in foreign nations. In addition, in many countries there is less publicly available information about issuers than is available in reports about issuers in the United States. Foreign companies are not generally subject to uniform accounting, auditing and financial reporting standards, and auditing practices and requirements may differ from those applicable to U.S. companies. Further, the growing interconnectivity of global economies and financial markets has increased the possibilities that conditions in any one country or region could have an adverse impact on issuers of securities in a different country or region.
The Administrator pays all fees and expenses that are directly related to the services provided by the Administrator to the Funds; each Fund reimburses the Administrator for all fees and expenses incurred by the Administrator which are not directly related to the services the Administrator provides to the Funds under the service agreement. Each Fund may also reimburse the Administrator for such out-of-pocket expenses as incurred by the Administrator in the performance of its duties. For these services each Fund that was operational for the period indicated paid the Administrator and Citi the amounts set forth below. Because the New Fund was not operational at the end of the Trust’s last fiscal year, information on fees paid to the Administrator and Citi on behalf of the New Fund is not included in this SAI.
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 Fund is an actively managed exchange traded fund. The Fund seeks to achieve its investment objective by investing substantially all of its assets in a combination of short positions in bitcoin futures contracts and money market instruments. The Fund is designed to benefit when the price of bitcoin futures contracts declines. The Fund generally seeks to have 30% of the value of its portfolio invested in short positions in bitcoin futures contracts and 70% of the value of its portfolio invested in money market instruments.

•   Tax Risk — In order to qualify for the special tax treatment accorded a regulated investment company (“RIC”) and its shareholders, the Fund must derive at least 90% of its gross income for each taxable year from “qualifying income,” meet certain asset diversification tests at the end of each taxable quarter, and meet annual distribution requirements. The Fund’s pursuit of its investment strategies will potentially be limited by the Fund’s intention to qualify for such treatment and could adversely affect the Fund’s ability to so qualify. The Fund can make certain investments, the treatment of which for these purposes is unclear. If, in any year, the Fund were to fail to qualify for the special tax treatment accorded a RIC and its shareholders, and were ineligible to or were not to cure such failure, the Fund would be taxed in the same manner as an ordinary corporation subject to U.S. federal income tax on all its income at the fund level. The resulting taxes could substantially reduce the Fund’s net assets and the amount of income available for distribution. In addition, in order to requalify for taxation as a RIC, the Fund could be required to recognize unrealized gains, pay substantial taxes and interest, and make certain distributions.

Certain debt securities may be treated as debt securities that were originally issued at a discount. Original issue discount can generally be defined as the difference between the price at which a security was issued and its stated redemption price at maturity. Original issue discount that accrues on a debt security in a given year generally is treated for federal income tax purposes as interest income that is included in a Fund’s income and, therefore, subject to the distribution requirements applicable to RICs, even though the Fund may not receive a corresponding amount of cash until a partial or full repayment or disposition of the debt security.

That's why liquidity and volume are essential to a quality exchange. If you enter that contract at $400 and you see bitcoin spot price jumping to $500 but nobody is trading futures so you can't sell it to them, you get screwed. Luckily at this point in 2016 there are numerous options for trading futures that are liquid and settle on short time horizons. So you can typically trade contracts and get in and out of them with decent spreads and reasonable fees.

On March 18, 2013, the Financial Crimes Enforcement Network (“FinCEN”) a bureau of the US Department of the Treasury, issued interpretive guidance relating to the application of the Bank Secrecy Act to distributing, exchanging and transmitting “virtual currencies.” More specifically, it determined that a user of virtual currencies (such as bitcoin) for its own account will not be considered a money service business (“MSB”) or be required to register, report and perform recordkeeping; however, an administrator or exchanger of virtual currency must be a registered money services business under FinCEN’s money transmitter regulations. As a result, Bitcoin Exchanges that deal with U.S. residents or otherwise fall under U.S. jurisdiction are required to obtain licenses and comply with FinCEN regulations. FinCEN released additional guidance clarifying that, under the facts presented, miners acting solely for their own benefit, software developers, hardware manufacturers, escrow service providers and investors in bitcoin would not be required to register with FinCEN on the basis of such activity alone, but that Bitcoin Exchanges, certain types of payment processors and convertible digital asset administrators would likely be required to register with FinCEN on the basis of the activities described in the October 2014 and August 2015 letters. FinCEN has also taken significant enforcement steps against companies alleged to have violated its regulations, including the assessment in July 2017 of a civil money penalty in excess of $110 million against BTC-e for alleged willful violation of U.S. anti-money laundering laws.
For purposes of the diversification test described in subparagraph (b) above, the term “outstanding voting securities of such issuer” will include the equity securities of a qualified publicly traded partnership. Also, for purposes of the diversification test in (b) above, the identification of the issuer (or, in some cases, issuers) of a particular Fund investment can depend on the terms and conditions of that investment. In some cases, identification of the issuer (or issuers) is uncertain under current law, and an adverse determination or future guidance by the IRS with respect to issuer identification for a particular type of investment may adversely affect the Fund’s ability to meet the diversification test in (b) above.

The Funds subject to the SEC “names rule” (Rule 35d-1 under the 1940 Act) have adopted non-fundamental investment policies obligating them to commit, under normal market conditions, at least 80% of their assets exposed to the types of securities suggested by their name and/or investments with similar economic characteristics. Such direct or inverse exposure may be obtained

As for why you should buy a put option instead of the asset itself, the answer is simple. By buying the asset itself, you can never profit from falling prices. With put options you can, simply because their value rises as the price of the underlying stock is falling. In addition to this feature, they offer the same kind of potential for leverage that calls options do, as described above. The price of put options is calculated in a similar manner, but with the important difference being that the intrinsic value is calculated as a predetermined price of the option minus the current market price of the asset – not the other way round as is the case for call options.