In 1999, 16 of the 27 countries in the European Union set out to unite and strengthen their economies by adopting the euro, a single currency. In 2002, physical coins and banknotes entered circulation.

Now, only seven years afterward, Standard & Poor's downgraded the economy of Spain from AAA to AA+ stating that the global economic crisis had heightened the "structural weakness" of Spain's economy. A key factor in lowering the credit rating was Spain's growing deficit, which is predicted to range from 5.8% to 6.6% of GDP. In addition, Spain's economy is expected to contract by 2% this year.

The downgrade has caused the spread between Spanish government bonds and German bonds to rise to record levels. The cost of insuring Spanish bonds through CDSs (credit default swaps) has also risen to record levels.

In addition to Spain, the economy of Greece was downgraded from A to A-. Portugal and Ireland are also at risk of being downgraded.

This brings into question just how long the euro can withstand further government downgrades without collapsing, and with Europe reverting back to single country currencies.

Is the euro falling apart at the seams?

One way investors/readers could characterize the current environment is as a world filled with concerns.

Concern about the U.S. housing sector. Concern about declining U.S. disposable income. Concerning about slowing GDP growth in Europe and Asia. Concern about the Yankees not winning the American League pennant.

O.K., that last item was a purely subjective, parochial one, but you get the point: there's concern that global economic conditions are worsening, not improving.

Europe's GDP is latest focal point

Further, while emerging markets in Asia, led by China and India, have been the growth story of the decade, the region really sending a chill up economists' -- business executives' -- spines is Europe, so says economist Glen Langan.

"Up through July we had seen weakness in Italy, Greece, Spain, and Portugal, and the investment community's response was one of 'no big deal, they are not the major growth regions, anyway,'" Langan said. "But now there's signs of slowing in Germany, France, and the United Kingdom, and nearly every demand-side indicator is in retreat. It's a pronounced psychological shift, no question."