昨夜，美國股市上響起警報，然而拉響警報的只是美國國債利率的微小變化。

美國當地時間周三上午，兩年期國債的利率略高于10年期國債利率，該現象就是收益率曲線倒掛。

截至收盤，道瓊斯工業指數下跌800點，跌幅3.05%。標普500指數下跌85.72點，跌幅2.93%。納斯達克指數下跌超過242點，跌幅3.02%。

別看唐納德·特朗普今天在推特（Twitter）上吐槽收益率曲線太瘋狂，要真正理解收益率曲線為何變得如此重要，以及此刻發送的信號是真是假，其實并不容易。

收益率曲線是比較不同期限國債利率的方法，比如說美國國債。在正常市場中，長期債券的利率（也就是收益率）應該高于短期債券的利率，因為投資者買長期債券要鎖定更長時間，期望獲得更高回報。

收益率曲線是不同期限的利率圖，比如3個月、6個月、一年、兩年、五年、10年、30年等等。各個點連接成線變成曲線。下圖就是例子，反映了2019年8月13日的收益率。

Alarms were going off in the stock market today. And what pulled the cord was a slight change in the interest rates of Treasurys.

Early Wednesday morning, the interest rate on a 2-year Treasury was slightly higher than the interest on a 10-year, an event called a yield curve inversion.

By market close, the Dow industrials were off 800 points, or 3.05%. The S&P 500 was down 85.72 points, which is 2.93%. And the Nasdaq lost more than 242 points, or 3.02%.

But understanding why the yield curve has gained such importance—even Donald Trump tweeted about the CRAZY YIELD CURVE today—and whether it’s sending true or false signals at the moment, is a little complicated.

Yield curves are a way of comparing the interest rates of the different maturity-date bonds a country issues—like U.S. Treasurys. In a normal market, interest rates (called yields) for longer-term bonds should be higher than those for shorter-term ones, because investors tie their money up for a longer time and want a greater reward for doing so.

The yield curve is a graph of the interest rates for varying maturities: like 3-months, 6-months, 1-year, 2-years, 5-years, 10-year, 30-year, and so on. A line is drawn through the plotted points to show a curve. Below is an example for the yields on Aug. 13, 2019.

即便沒有出現10年期收益率短暫略低于兩年期，該收益率曲線也不正常。

收益率曲線倒掛

通常曲線會向上彎曲，因為圖左側的短期債券到期收益率通常低于右側的長期到期收益率。

然而有時短期債券的收益率比長期債券高，導致曲線向下彎曲。這被稱為收益率曲線倒掛，因為與人們通常期望的相反。

倒掛之所以重要，因為該現象是判斷經濟衰退即將到來的重要指標。短期利率高于長期利率時，表明未來可能出現經濟衰退，因為收益率數字顯示投資者認為短期經濟比長期經濟更有把握。

這種情況下，曲線不會平滑向上，也不會明顯下滑，而是中間出現凹陷，而且不只持續一分鐘。

之前的倒掛

“通常來說，倒掛發生在衰退12到18個月之前。” Regency Wealth Management公司的合伙人安德魯·阿蘭表示。但倒掛只是指標之一，最近幾次倒掛時，之后實際出現經濟衰退的幾率只有三分之二。

今天的倒掛與過去還不一樣。“二戰以來美國每一次經濟衰退之前，除了2007年以來的經濟大衰退，都出現過美聯儲加息太多太快，遠高于當前水平的水平。”馬里蘭大學的金融學教授大衛·卡斯冷靜地分析道?？ㄋ狗Q大衰退的例子“獨一無二”，主要根源是“房地產市場債務過多，樓市和經濟崩潰”。

但美聯儲剛剛宣布降息25個基點，投資者預計到今年年底還會小幅降息多達三次。至于債務方面，“各板塊都沒有出現債務過多的跡象?！笨ㄋ贡硎?。

到底發生了什么？

上面圖表中并未明確顯示出倒掛。超短期利率為2.05%，五年期降至1.57%的低點，30年期升至2.15%。長期收益率略高于短期收益率。但兩年期至10年期的收益率很低。

“一般來說，有一點不同的是曲線整體呈平緩趨勢?！盇viva Investors的投資組合經理蒂姆·阿爾特表示。長期經濟趨勢方面，人們預期不一定出現問題，但對中期前景感到緊張?！耙环N解釋是，市場認為景氣周期放緩的可能性較低，但最終將陷入衰退的可能性較高?！彼f。還有人擔心，央行在刺激經濟方面可能已經無計可施。“值得關注的是，市場越發相信財政政策是唯一能起推動作用的手段。”阿爾特說。

這意味著政治家們應該合作并采取有效措施，可能涉及到采取投入資金刺激經濟。但合作很難實現。

其他問題

市場的反應則讓許多人困惑。

“理解債券市場反彈很容易理解?！?Wedbush Securities的投資組合經理史蒂夫·馬紹卡表示?！安贿^股市下跌很奇怪，而且是各板塊集體跳水。”

“今天（銀行股）遭大舉拋售，但貸款定價對短期利率更敏感?！睂嶋H情況是短期利率堅挺，阿蘭表示。“這可能是另一種過度反應，一早就把銀行打倒在地?！?/p>

可能根本原因還是神經緊張。與中國和歐盟的貿易爭端讓許多人恐懼。歐洲經濟整體放緩，歐洲和日本仍然維持負利率。隨著收益率曲線倒掛，市場似乎把所有事都當成壞消息。

不管是過度悲觀，還是投資者神經過敏，都在將市場推向真正的衰退。（財富中文網）

譯者：Feb

This is not a normal yield curve, even without a brief time where the 10-year yield was a little lower than the 2-year.

Yield curve inversion

Typically, the curve bends upwards because the shorter-term maturities on the left of the graph have lower yields than the long-term maturities toward the right.

However, sometimes shorter-term maturities offer higher yields than longer-term ones, resulting in the curve sloping downward from left to right. That’s called a yield curve inversion, because it does the opposite of what people typically expect.

Inversion is important because of its status as an indicator of coming economic recessions. When short-term rates are higher than long term, it indicates the potential for a future recession because the numbers indicate that investors think the short-term economy is a better bet than the long term.

In this case, instead of a clear climb one way or the other, there’s a dip in the middle—more on that in a minute.

Past inversions

“Typically these inversions occur 12 to 18 months before a recession,” said Andrew Aran, a partner at Regency Wealth Management. But an inversion is just an indicator, as in recent times, only two-thirds of them have actually come before a recession.

But the inversion today is different from the past. “Every recession that we’ve had in the U.S. since World War II, with one exception of the Great Recession, was preceded by the Federal Reserve raising interest rates too far, too fast from much higher levels than the current levels,” said David Kass, clinical professor of finance at the University of Maryland. The Great Recession, which Kass called “one of a kind,” was the result of “an excessive amount of debt in the housing market and the collapse of the housing market and the economy.”

But the Fed just dropped the rate by 0.25% and investors expect as many as three more small cuts by the end of the year. As for debt, “I don’t see an excessive amount of debt in any sector,” Kass said.

What’s going on?

The pattern of the graph above is also not a clear inversion. Very short-term rates start at 2.05%, drop to a low of 1.57% for the 5-year, and then climb to 2.15% for the 30-year. The long-term yield is a bit above the shortest-term. But yields on the 2-year through 10-year are low.

“Generally speaking is what is a little different is a broad flattening across the curve,” said Tim Alt, portfolio manager at Aviva Investors. People may not expect trouble in the long run but are nervous about medium-term prospects. “One way to interpret that is the market is pricing in lower odds that this is a mid-cycle slowdown and higher odds that it is going to end up in a recession,” he said. There is also worry that central banks may have run out of tricks to stimulate the economy. “The concern is that the market is moving toward believing that fiscal policy is the only thing to move the needle,” Alt said.

That means getting politicians to cooperate and forge useful actions that probably involve spending money to stimulate the economy. Such cooperation is going to be hard to find.

Other concerns

But the market’s response has left many scratching their heads.

“I certainly understand the rally in [bonds],” said Steve Massocca, portfolio manager at Wedbush Securities. “The decline in equities is a mystery. And it’s across the board.”

“[Bank stocks] are being sold aggressively today, but their pricing on their loans is more sensitive to short rates” and short rates are holding, Aran said. “That seems to be possibly another over reaction, taking the banks behind the woodshed at an early point.”

It may all come down to a case of nerves. Trade disputes with China and the EU are scaring many. Economies across Europe have slowed, with negative interest rates still in place there and in Japan. The markets seem primed to take everything at the moment as bad news, as the yield curve enters new territory.

Either that or jittery investors are about to talk themselves into a recession.