The CEO of J.P. Morgan this week called bitcoin a "fraud" and "worse than tulip bulbs." If you agree, it may be tempting to bet against the digital currency. Sure, the price has taken a beating of late but it's still up 400% from January ($3,850 as of Thursday) —offering an opportunity for bitcoin bears.

So how exactly do you short bitcoin? It's not easy due to a lack of financial products (relative to other assets) and because some tactics are restricted to professional investors. That said, here are five approaches for bears to bet against the world's most popular digital currency.

1) Buy it on margin and then sell it

Trading platforms like Coinbase-owned GDAX allow you to buy on margin. While margin purchases typically involve adding leverage to go long on an asset, it's also possible to go short by selling bitcoins on margin, and then closing out the position later on. If the price of bitcoins drops during this time, you'll profit on the trade.

There are a couple caveats. One is that GDAX requires U.S. residents to have at least $5 million if they want to trade on margin. (San Francisco-based rival Kraken doesn't appear to have this restriction). The other is that customers can only leave margin positions open for a relatively short period of time—27 days in the case of GDAX—which means those betting on a fall in bitcoin need it to tumble in short order, or else they will have to cover the price increase.

2) Short shares of the Bitcoin Investment Trust

The SEC this year rejected an application by the Winkelvoss twins to launch a bitcoin ETF. The shares of the ETF would have traded on a major exchange, and let ordinary investors use their brokerage accounts to short them in the same way as an ordinary stock.

The SEC is reconsidering the decision but, in the meantime, the only stock-like alternative is the Bitcoin Investment Trust. As its name suggests, this is a trust that holds bitcoin and lets people trade its shares under the ticker GBTC.

Once again, there are catches. One is that GBTC is not eligible to trade on major exchanges, so instead it's listed on OTC Markets (aka the "pink sheets") alongside other misfit toys of the equities world. Big brokerages like TD Ameritrade do let investors buy OTC-listed stocks—but not short them, which makes it harder to bet against GBTC. Finally, the price of Bitcoin Trust shares have become untethered to the price of bitcoin (it's basically broken as an investment vehicle) so a short bet is not exactly a bet on bitcoin itself.

3) Buy derivatives on LedgerX (when they arrive)

Experienced investors may wish to wade into the world of options and other derivatives as a way to be bearish on bitcoin. Specifically, they could buy a "put option" to sell bitcoin at its current high-flying price. If the price of bitcoin starts dropping, the option will increase in value and its owner can pocket a profit.

These derivative contracts are not available yet, but they should be soon. In July, the Commodity Futures Trading Commission approved a bid by a firm called LedgerX to open a clearinghouse for crypto-currency puts, calls, swaps and all sorts of other exotic contracts. LedgerX is expected to be open for business in the near future.

(Update: There's also Hong Kong-based Bitmex, which is a long-time purveyor of bitcoin-related derivatives. One catch: all transactions, as well as profits and losses, are conducted in bitcoin—meaning you must buy bitcoin before you can short it).

4) Ask Goldman Sachs to write you a contract

This approach is admittedly not for Joe Blow investors. It came up when I asked a few wealthy VCs at a recent dinner how they would short bitcoin given the current absence of derivatives and other common trading strategies.

Their answer was that investment banks like Goldman will write you a short position on anything you like. (Remember that scene in The Big Short when the protagonists ask banks to help them short the U.S. housing market?). So someone who believes bitcoin is a bubble could create a bespoke contract to bet on just that outcome.

5) Pick stocks that track bitcoin prices—and short them

Nikhil Kalghatgi, a venture capitalist and early digital currency investor, believes the cryptocurrency market is hindered right now by a shortage of ways for big investors to deploy hedging strategies. In response, he suggests one way to bet against bitcoin is to create a basket of stocks that move with the price of bitcoin and short them accordingly. Alas, Kalghatgi says he is not confident enough to pick what those stocks would be.

He's not the only one to propose this idea. The Financial Times'Alphavilleblog recently singled out shares of the chip maker Nvidia, whose products are hugely popular with cryptocurrency miners, as a potential proxy for those looking to short bitcoin. But Nvidia makes products for all sorts of other industries, so using it as a bellwether for bitcoin would be a crude metric.

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The bottom line is that, for now at least, there is no simple way for ordinary investors to short bitcoin. Determined bears can and will find ways to do so—but everyone else might want to hold out for a bitcoin ETF or derivatives to arrive.

上周摩根大通的首席执行官痛斥比特币为“骗局”，“比荷兰郁金香泡沫还恶劣。”如果你同意他的说法，可能会想到做空。摩根大通高管抨击以后，比特币交易价确实出现下挫，虽然价格较今年1月仍涨了四倍（本周二价格为每个3850美元）。没准，做空比特币的机会真来了。

怎样才能做空全球人气最高的数字货币——比特币？由于（和其他资产相比）比特币相关的金融产品比较少，而且某些手段只有专业投资者才会操作，普通人想做空并不容易。不过采用以下五种方法还是可以实现的。

1）通过保证金交易买入比特币，然后抛售

通过Coinbase旗下的GDAX之类比特币交易平台，用户可以通过保证金买入。虽然保证金买入交易通常用于加杠杆做多某项资产，但也可以通过保证金卖出比特币，之后再平仓。如果比特币价格在交易期间下跌，就可以获利。

用这种方法需要注意几点。一是GDAX要求，如果美国公民希望利用保证金交易，其个人可支配投资金额至少得有500万美元（总部位于旧金山的交易平台Kraken看来并没有相关限制）。二是保证金交易的持仓时间相对较短，比如GDAX允许持仓最多27天。这意味着，做空客户赌的是比特币短期内会下跌，否则将不得不回补空单，弥补比特币涨价的损失。

2）做空比特币ETF

今年美国证券交易委员会拒绝了双胞胎文克莱沃斯兄弟推出比特币交易所交易基金（ETF）的请求。若这一申请获批，该ETF的股份就可以在大型交易所交易，普通投资者能像做空普通的个股一样，通过个人投资账户做空比特币ETF。

SEC正在重新考虑之前的决定。在此期间，唯一一个类似股票可供做空的选择是ETF Bitcoin Investment Trust。顾名思义，Bitcoin Investment Trust是一只对标比特币的信托基金，交易代码为GBTC，投资者可以买卖份额。

这种方法也有要注意的事项。一是GBTC还没能登陆大交易所，只能在场外交易市场（OTC）（所谓“粉单”市场）交易，和尚未满足上市标准的证券一样买卖。投资者通过TD Ameritrade之类大经纪商可以购买OTC交易的证券，但不能做空，所以做空GBTC难度更大。最后要指出，GBTC的交易价已经和比特币价格（基本上GBTC已经变成单纯的投资工具）脱钩，所以做空GBTC并不完全等于做空比特币。

3）在期权交易所LedgerX购买比特币的衍生品（实际推出后）

经验丰富的投资者可能希望借道期权和其他衍生品做空比特币，尤其是买入“看跌期权”，日后以当前的高价卖出比特币。如果比特币交易价开始下跌，看跌期权就会增值，持有者就可以获利。

目前市面上还没有这种衍生品合约，但应该很快问世。今年7月，一家名叫LedgerX的公司获得美国商品期货交易委员会（CFTC）批准成立清算所，处理虚拟数字货币看跌和看涨期权、掉期合约和其他各类衍生品合约的交易和清算。预计LedgerX很快就会开展业务。

（更新：位于香港的Bitmex一直是处理比特币相关衍生品交易的平台。要注意的是，该平台的所有交易都通过比特币进行，包括计算盈亏，所以在做空比特币以前必须先买入比特币。）

4）请高盛帮你做空

这种方法不太适合一般投资者，我是在咨询一些很有钱的风投基金时听说的。最近有一次吃晚饭时我问风投大佬们，既没有衍生品也没有其他常用的交易手段时怎样做空比特币。

他们的答案是，高盛之类投行可以帮你交易空单，做空任何标的。（大家还记得电影《大空头》的主人公请银行帮忙做空美国房产市场吗？）因此，如果相信比特币是个泡沫，也许可以定制合约押注比特币崩盘。

5）做空追踪比特币价格的个股

风险资本家、数字货币兴起之初的投资者尼克希尔·卡尔加特基认为，加密数字货币市场如今发展遇阻，因为大玩家缺少进行对冲的策略。对此他提出了一种做空比特币的方法：挑选一些追随比特币价格而动的个股建立投资组合，然后逐个做空。但卡尔加特基也承认将相关股票挑出来不太容易。

卡尔加特基不是唯一一个提出这种方式的。英国《金融时代》的博客Alphaville最近将芯片制造商英伟达列为做空比特币的标的，因为英伟达的产品在挖矿加密数字货币的行当中十分受欢迎。然而英伟达还有其他领域的产品，简单将其当成比特币龙头股有点简单粗暴。

归根结底，普通投资者想做空比特币的话现在还没什么简单的方法。如果坚定看空，自然能找到做空的方法。如果没那么笃定，或许要等到比特币ETF或者衍生品上市再做打算了。（财富中文网）

译者：Pessy

审稿：夏林