Negative yielding debt is the most striking consequence of aggressive central bank policy. The amount of bonds with negative market interest rates is near $7tn and appears set to grow. Buying a bond with a negative yield, and holding it to maturity is a guaranteed way to lose money. So why would anyone do so?

负收益率债券是央行激进政策最令人瞩目的后果。目前市场利率为负的债券总计接近7万亿美元，且仍呈增长势头。购买收益率为负的债券然后持有到期，绝对是个赔本买卖。那么为什么有人会这样做呢？

Because central banks will keep buying

因为央行将继续购买

Central banks have sought to stimulate economies through bond purchases. They hope to encourage lending by cutting borrowing costs, with the ultimate aim of boosting economic growth. Negative bond yields are a feature of this policy, not a bug.

各国央行试图通过购买债券来刺激经济。他们希望削减借款成本，以鼓励放贷，最终目的是促进经济增长。负收益率债券不是该政策的缺陷，而是它应有的特点之一。

The lower the yield on a bond, the higher its price. If a bond pays a coupon of 1 and has a price of 104, and it matures in a year at 100, the yield, or return, is negative. So negative yields are a simply a reflection of extremely high prices, which could be pushed higher by further demand such as central bank purchases.

债券收益率越低，其价格就会越高。如果债券的票息为1，价格为104，一年后以100的价格到期，收益率就为负。因此负收益率只是反映了债券价格极高，而且可能被进一步需求——比如央行购买——推到更高水平。

Because you have to

因为你不得不买

Institutions and investors which buy bonds and shares globally, are constrained by mandates, sets of rules dictated by the banks, pension funds or insurance companies from whom the money comes.

机构和投资者在购买全球债券和股票时，受到委托权限的限制，即银行、养老基金或保险公司等出资方规定的种种规则。

The layered bureaucracy of the buyside can effectively force some investors to buy negative yielding debt. Money market funds, for example, typically invest in bonds up to a maturity of 13 months. For large amounts of the euro government debt market, bonds of a maturity shorter than this are negative yielding; German government bonds are negatively yielding up to a maturity of eight years.

买方的多层次官僚规则可能在实际上迫使一些投资者买入负收益率债券。例如，货币市场基金一般只可投资于到期时间不超过13个月的债券。在欧元区政府债券市场，符合这个要求的大量债券的收益率为负值；到期时间8年或以下的德国国债收益率全部为负值。

For some clients, regulatory requirements may force them to buy certain types of assets — banks, for example, are required to hold liquid assets.

对于部分客户来说，监管要求可能会迫使他们购买某些特定资产，比如银行就必须持有流动资产。

It’s better than holding cash

买它比持有现金好

Buying negative yielding debt might be considered similar to paying a government to guard your money in a vault. Government debt, though, is “liquid” — it can be bought and sold swiftly at little cost.

购买负收益率债券可能被视为类似于付钱给政府，由其把你的钱守护在金库里。不过政府债务是“流动的”，以较小的代价就可以迅速买入和卖出。

Investors need returns, but they must balance this with a need for liquidity — providing their clients with rapid access to cash or cash-like assets.

投资者需要回报，但他们必须在回报需要与流动性需要（为他们的客户提供快速获得现金或现金类资产的途径）之间进行权衡。

Cash is the most liquid of assets. But central banks have imposed negative interest rates on cash deposits, which stands to trickle through to the rate banks charge institutional investors. A highly liquid but slightly negative yielding government bond might look more attractive by comparison.

现金是流动性最强的资产。但某些央行已对现金存款实行负利率，这会渐渐导致银行对机构投资者的存款实行负利率。相比之下，收益率为微小负值、但具有高度流动性的国债可能看起来更具吸引力。

Because the world is terrifying

因为这个世界越来越可怕

Negative yields as a phenomenon reflect the challenges of central bank policy and expectations around economic growth. In a stagnant world, negative yielding bonds are both signal of and hoped for remedy to deflation.

负收益率债券现象反映了央行政策面临的种种挑战，以及围绕经济增长的预期。在经济增长停滞的世界里，负收益债券既是通缩的信号，也是人们指望的通缩解药。

Global equity markets have been rocked by economic fears so far in 2016. Not only might these fears consolidate the view that growth will slow further and push bond prices higher — they may also encourage investors with some flexibility to move their allocations away from risky assets and towards havens, reasoning that a small loss will constitute “over-performance” if other asset classes take double-digit losses.

2016年以来全球股市受到经济担忧的震动。这些担忧不仅可能强化这样一个观点，即增长将进一步放缓，推动债券价格走高，还可能鼓励具有一定弹性空间的投资者把更多资产配置到避险资产、减持风险资产，其逻辑是：如果其他资产类别遭受两位数的降幅，那么小幅亏损将构成“超常表现”。

As fears grow, demand for haven assets grows. With bonds, this can push prices so high that yields turn even more negative. The supply of bonds, in a world where governments seek to curtail the levels of spending seen in the past, could also be constrained. These long-term dynamics could normalise permanently lower, if not negative, yields. They certainly seem different to the dynamics of the economies in which the modern bond market was shaped.

随着担忧加剧，对避险资产的需求也在增长。这会推高债券价格，导致收益率在负值区间进一步下行。在各国政府寻求将支出削减到以往水平的背景下，债券供应也可能会受到制约。这些长期动态可能令低收益率——即使不是负收益率——常态化。它们肯定与塑造现代债券市场的经济动态不同。

What’s the downside?

负收益率债券有哪些缺点？

The danger, and one of the great ironies in a world of negative yielding bonds, is that prices for instruments designed to be safe and dull have become volatile. Consider the German 10-year Bund yield, not yet negative, which last spring unexpectedly surged back towards 1 per cent.

负收益率债券世界的危险和最大讽刺之一是，以安全和乏味为设计宗旨的这类工具的价格变得波动。德国10年期国债收益率——尚未转负——去年春天意外曾飙升到近1%的水平。

But ever lower yields mean capital gains — a reward for the continual risk of changing policy. Investors who bought German Bunds at the start of the year have made 4.2 per cent so far in 2016, according to Barclays government bond indices. Not a bad return, if the world is falling apart.

但是即便是较低的收益率也意味着资本收益，算是对政策不断改变带来的持续风险的回报。据巴克莱(Barclays)政府债券指数，今年初购买德国国债的投资者迄今已获得4.2%的账面利润。这一回报还算不错——假如世界正在分崩离析。