度過了較為平靜的幾個月后，數字加密貨幣市場再次全面崩潰。比特幣跌破了6000美元的長期底部，而且上周所有加密貨幣都下挫了10%以上。

唯一的例外是所謂的穩定幣，這種虛擬貨幣的設計宗旨是保持1美元的固定價值。在理論上，當加密貨幣全面暴跌時，它們應該成為避風港。但它們能堅持得住嗎？

到目前為止，穩定幣的情況都還讓人安心。三大穩定幣—— Paxos、TrueUSD和加密貨幣金融公司Circle支持的USD Coin的價格實際上都有1.01或1.02美元。這是好消息。

但壞消息是規模最大的穩定幣Tether發出了醒目的警示信號。《金融時報》旗下的博客Alphaville指出，Tether早在今年10月就已經“跌破1美元”，目前的價格為0.98美元。

理論上不應該出現這樣的局面，如果Tether確實值1美元，那么套利者就會趁虛而入并迅速將其價格重新推上1美元的基準線。但實際情況并非如此，那就是說出了問題。

對熟悉Tether的人來說，說它暗藏玄機不是什么新鮮事。長期以來，批評人士一直在指責Tether團隊，因為他們拒絕提供正當審計結果，以表明自己是在用真金白銀來支持這種加密貨幣?，F在又有報道稱，Tether團隊的新合作銀行，總部設在巴哈馬群島的Deltec Bank是一家涉嫌洗錢的“狡猾”機構。

問題還不止這些——和Tether關系密切的加密貨幣交易所Bitfinex，看來已經為打算將加密貨幣套現的主要投資者新設置了嚴格的提款手續費。正如加密貨幣博客News BTC所述，人們已經開始質疑此舉是否意在防止Tether遭到全面擠兌，據說投機者已經對Tether下手了。

所有這些帶來的問題是，如果新一波投機證明Tether并無盯住美元的手段，那會出現什么情況呢？倘若實際情況證明目前的第八大加密貨幣Tether的真實價值為0.75或0.50美元，或者更低，那么由此給加密貨幣市場帶來的沖擊可能會讓本周的暴跌看上去就像“撓癢癢”。

好的一面是其他穩定幣看來確實得到了美元的等額支持。但它們絕不是投放資金的理想對象?，F在就連普通儲蓄賬戶的利率都達到了2%，穩定幣卻不產生絲毫利息。另外，購買穩定幣還要支付手續費，而眼下這些“受尊敬”加密貨幣的價格只有1美元零1美分。

綜上所述，穩定幣聽上去是一筆失敗投資——當然，除非大家拿它們跟目前市場上的其他加密貨幣相比。（財富中文網）

譯者：Charlie

審校：夏林

Cryptocurrency markets, after months of relative calm, are melting down all over again. Bitcoin crashed through its longtime floor of $6,000 and digital tokens of all types fell more than 10% in the past week.

The one exception has been so-called stablecoins, virtual currencies designed to maintain a fixed value of $1. In theory, they should be a safe haven from the larger crypto carnage. But will they hold up?

So far, the stablecoin situation has been reassuring. Three of the biggest—Paxos, TrueUSD and Circle-backed USD Coin—are actually trading a cent or two above $1. That’s the good news.

The bad news is the largest stablecoin of them all, Tether, is flashing a giant warning sign. As the Financial Times’ blog Alphaville notes, Tether has been “breaking the buck” since October and is currently underwater at 98 cents.

In theory, this shouldn’t happen. That’s because, if Tether is truly worth $1, arbitragers will swoop in and quickly drive it back to its baseline price of a buck. That’s not happening, which means something is wrong.

Word that something is fishy about Tether will not be news to anyone familiar with it. Critics have long decried the refusal of the Tether team to provide a proper audit to prove they are backing the currency with real dollars. And now come reports that its new banking partner, Bahamas-based Deltec Bank, is a dodgy outfit accused of money laundering.

More troubling still: Bitfinex, a cryptocurrency exchange tied to Tether, appears to have put in stiff new withdrawal fees for large investors that want to cash out their crypto holdings. As cryptocurrency blog News BTC notes, folks are already asking if this move is intended to halt a full-blown run on Tether, which is reportedly under attack from speculators.

All of this raises the question of what happens if another speculative attack proves nothing is pegging Tether to the dollar, and the price goes into free fall. If it turns out the true value of Tether—currently the eighth biggest cryptocurrency—is 75 cents or 50 cents or less, it could deliver a shock to the crypto markets that makes this week’s wipeout look like a hiccup.

The bright side is other stablecoins do appear to be backed by dollars on a one-to-one basis. Still, they are hardly a great place to park your money. At a time when even a simple savings account can earn you 2%, stablecoins pay nothing in the way of interest. What’s more, there are transaction fees to acquire them and, right now, the respectable ones are trading for a cent above the dollar.

All in all then, stablecoins sound a rotten investment—unless, of course, you compare them to the rest of the crypto market right now.