The S&P 500 is lower by about 0.2 percent, bucking much sharp losses overseas. Germany's DAX fell by more than 1.5 percent, and France's CAC-40 shed 2 percent as investors return to "worry mode" over economic growth and the continent's fiscal problems. Attention is now focusing on Spain, which faces protests over the prospect of increased austerity measures.
Asian markets fell by 1 percent to 2 percent, also on concerns about global growth. The economic picture has worsened in recent weeks, seen in German business confidence and weak forecasts from companies such as FedEx, Caterpillar, and now contract manufacturer Jabil Circuit.
Foreign-exchange markets are showing the typical patterns of risk aversion, with the euro, Canadian dollar, and Australian dollar all down against the U.S. dollar. The Japanese yen is higher across the board.
The direction of commodities is less clear. Oil and copper, which are most leveraged to the strength of the economy, are falling by more than 1 percent. Gold and silver, which usually enjoy something of a safe-haven status, are posting much smaller losses. Most agricultural foodstuffs are lower by more than 1 percent.
In company-specific news, JBL fell by more than 4 percent in extended trading yesterday after weak demand caused management to issue a forecast below analyst expectations. Synnex, a supplier of electronic components, also gave weak guidance and dropped almost 4 percent. Neither has traded yet in the pre-market today.
The main reports on today's calendar will be new home sales at 10 a.m. ET, which could provide a positive catalyst because U.S. housing has been one of the stronger segments of the economy. Oil inventories follow half an hour later, but those have been more bearish of late.

