Market Signals: A look at what has changed in financial markets in the last month

What a difference a month makes.

On Sept. 18, the U.S. stock market reached a record high after a mostly uneventful summer. Long-term interest rates headed higher, a sign that investors expected steady U.S. growth. A widely watched measure of volatility in the U.S. stock market was near its lowest level of the year, and European markets were heading higher after a nasty downturn over the summer. The price of crude oil was declining, but nothing like the sudden plunges that would come weeks later.

Here is a snapshot of key market signals and what they've shown over the last month and year to date.

S&P 500 INDEX

It's been a bumpy ride for U.S. stocks in the last month, especially since Monday. The Standard & Poor's 500 index nearly went into "correction" on Wednesday, meaning a decline of 10 percent or more from a recent peak. The declines briefly wiped out the year-to-date gains for the index.

One month: Down 5.7 percent.

Year-to-date: Up 2.1 percent.

BONDS

The U.S. Treasury market had one of its biggest moves in recent memory on Wednesday. The yield on the 10-year Treasury note dropped precipitously as prices on the notes surged. A rush to buy U.S. government debt, which is seen as extremely low-risk, can indicate investors are fearful of disruptions in other markets or expect the U.S. economy to slow down. In one morning the yield dropped from 2.20 percent to as low as 1.91 percent, a huge move that would normally take weeks. The magnitude and suddenness of the drop shocked investors, and left many puzzled over what caused it. By the end of the week trading had stabilized.

Friday: 2.20 percent.

One month ago: 2.62 percent.

Beginning of the year: 2.97 percent.

CRUDE OIL

The price of crude oil has had some steep drops in recent weeks, and has been in more or less steady decline since hitting a peak of $107.26 a barrel in June. On Friday it closed at $82.75 a barrel, 23 percent below that peak. Ample global supplies, high production levels and expectations of slowing demand in China and in Europe as economic growth weakens have driven down the price of oil. While cheaper prices for oil and gas are good for drivers, airlines and many others, they mean trouble for energy company profits.

One month: Down 12.2 percent.

Year-to-date: Down 15.7 percent.

EUROPE

Troubling signs of a slowdown in Germany, Europe's biggest economy, have rattled investors in recent weeks. Also, Germany's resistance to using economic stimulus puts it at odds with the European Central Bank and its European neighbors. That contributed to a slide in European markets over the last month. The declines were even more pronounced in countries on the periphery of Europe, which have borne the brunt of the region's long-simmering government debt problems, such as Greece and Portugal. Greece was especially hard hit by fears that its government could collapse, jeopardizing its exit from bailout loan programs. Greece's long-term borrowing costs rose sharply, a signal that investors are more worried about its ability to pay its debts.

Germany's DAX

One month: Down 8.4 percent.

Year-to-date: Down 7.3 percent.

Portugal's PSI

One month: Down 13.9 percent.

Year-to-date: Down 23.1 percent.

Greece's ATHEX

One month: Down 17.7 percent.

Year-to-date: Down 19.9 percent.

Yield on Greece's 10-year bond

Friday: 7.93 percent

One month ago: 5.77 percent

Beginning of the year: 8.14 percent.