Elvin Mirzayev 2016年7月14日
負利率的想法看起來很奇怪而且不能用經典金融和經濟理論來解釋，因為經典金融和經濟理論都是建立在正預期回報上的假設。傳統上，投資者有規避風險的特性並且在各個風險水平需要獲得不同的回報增量。
但是現在我們發現有負央行存款利率和負收益政府和公司債券的出現，並且有投資者購買這些證券。這是為什麼呢？
歐洲央行的負存款利率
央行將負存款利率當作一個阻止央行出現超額資金的貨幣政策。
例如，今年3月歐洲央行（ECB）將存款利率設置為-0.4%。這是一個改變利率中極其極端的貨幣政策，與央行削減利率刺激經濟活動很相似。
歐洲國家現在正與負通脹率作鬥争，歐洲央行選擇將存款利率降低到負值以推動過剩資金投入到經濟中。他們的目標是銀行將會受到負利率存款的刺激從而使用資金將基準利率維持在0，將回購利率維持-0.1%。瑞士和丹麥央行也同樣採用了負利率作為貨幣政策工具。
負收益債券
在上週，德國首次將10年期債券的收益率設定為負值。負債券收益表明投資者願意支付費用去持有德國債務。現在全球負收益債券的數量超過8萬億美元。
投資負收益債券的原因如下：
u 擴大的負收益預期。在當前通貨緊縮的經濟環境下，購買負收益債券的投資者可能會期望債券的收益率進一步降低，使他們能夠從投資中獲利。
u 正收益的可能。在預計會發生通貨緊縮的經濟中，投資負收益債券的投資者可能會獲得實際的正收益。
u 重新分配資金減少負收益。因為一些央行的實行的負利率高於政府債券的負收益，投資者更情願從央行取出資金投資債券，這將減少損失。
u 分配策略。一些機構投資者需要在其投資組合中持有債券，特別是那些專註於固定收益投資的投資者，他們可能需要投資負收益債券以滿足分配政策。
u 貨幣升值預期。一些投資者估計某些貨幣會相對本國貨幣計價的負利率債券升值，他們認為投資會帶來本國貨幣的正收益。例如，加入A國債券收益率比B國高負收益率債券高，但是投資者預計B國貨幣會相對A國貨幣升值，這樣投資B國債券帶來的回報可能高於投資A國債券。
u 資金安全考慮。新興市場國家的投資者在經濟衰退中舉步維艱，隨時面臨著違約和貨幣貶值，他們將會願意購買歐洲經濟大國的債券避險，例如德國和瑞士等。
總結
歐元區與通貨緊縮的鬥争導致了令人費解的負收益債券和負央行存款利率的出現。很難解釋投資者為什麼會投資這些確定會出現損失的工具，但是可能的原因是：擴大的負收益預期、通貨緊縮預期的加大、貨幣匯率變化和尋求安全投資。
The Negative Rates of Europe's Central Banks
By Elvin Mirzayev, CFA, FRM | Updated July 14, 2016 — 11:22 AM EDT
The idea of negative interest rates seems strange and isn't explained by classic financial and economic theories, which are all built on the assumption of positive expected return. Traditionally, investors are risk averse and require a positive incremental return for every level of risk taken.
But now that we are seeing negative central bank deposit interest rates and government and corporate bonds with negative yields, there are investors buying into these securities. Why?
Negative Deposit Rates Of Europe's Central Banks
Central banks apply negative interest rates to the deposit as a monetary policy tool to discourage banks from depositing their excess cash with the central banks.
For example, the European Central Bank (ECB) set depositary rates at -0.4% this past March, meaning that it was penalizing banks that hold excess cash with the central bank. It’s an extreme execution of monetary policy, which includes changing interest rates, much like when central banks decrease the rates to stimulate economic activity.
EU countries are currently battling negative inflation i.e. deflation, and the ECB chose to decrease deposit interest rates below zero in order to push banks' excess cash into the economy. The expectation is that banks will be discouraged from negative investing and instead will use the funds to maintain the reference rate at zero and the repo rate at -0.1%. Central Banks of Switzerland and Denmark also apply negative yields as a monetary policy instrument.
Negative Yielding Bonds
Just this past week, Germany began auctioning 10-year bonds at negative yield for the first time. Negative bond yields imply that investors are willing to pay the German government to hold its debt. Including Brexit, there are now over $8 trillion in negative-yielding bonds in the world.
The rationale behind investing in bonds that offer a guaranteed loss:
Widening negative yield expectation - Under the current deflationary economic environment, investors who purchase negative yielding bonds may expect the yields to decrease even further, enabling them to profit from the investment.
Possibility of a positive real return - In economies where deflation is expected, investors may end up with positive real yield by investing in negative yield bonds.
Reallocating cash from more negative to less negative - Since some central banks apply negative yields that are higher than negative government bond yields, investors prefer to withdraw cash from central banks and invest in government bonds which will cost less.
Policy allocation – Some institutional investors are required to maintain bonds in their portfolio - particularly investors who specialize in fixed income security investments like bond mutual funds - and they may keep investing in negative yielding bonds in order to be in line with that policy allocation.
Currency appreciation expectations – Foreign investors who expect an appreciation of currency against a domestic currency-denominated bond with a negative yield would agree to invest for the positive expected return in the domestic currency. For example, if Country A's bonds has a higher yield than Country B's negative yield bonds, but investors expect Country B's currency to appreciate in value relative to Country A's currency, investing in Country B's bonds may result in higher returns.
Paying for safety - Foreign investors from emerging countries struggling with economic downturns, accompanied by defaults and currency devaluation, would agree to safe-haven buying bonds with negative yields in Europe's economic giants like Germany, Switzerland etc.
The Bottom Line
The Eurozone's fight with deflation results in inexplicable negative bond and central bank deposit rates. It’s difficult to see why investors would be willing to invest in instruments that offer a guaranteed losses, but possible reasons are: negative yield widening expectations, increasing deflation expectations, currency rate change and seeking safe investments.
本文翻譯由兄弟財經提供
文章來源：http://www.investopedia.com/articles/investing/040215/understanding-negative-rates-europes-central-banks.asp