Economic trouble has spread far beyond the United States to major countries in Europe and Asia, threatening American businesses with the loss of foreign sales and investment that have become increasingly vital to their sustenance.

Only a few months ago, some economists still offered hope that robust expansion could continue in much of the world even as the United States slowed. Foreign investment was expected to keep replenishing American banks still bleeding from their disastrous bets on real estate and to provide money for companies looking to expand. Overseas demand for American goods and services was supposed to continue compensating for waning demand in the States.

Now, high energy prices, financial systems crippled by fear, and the decline of trading partners have combined to choke growth in many major economies. The International Monetary Fund expects global growth to slow significantly through the end of this year, dipping to 4.1 percent from 5 percent in 2007.

“The global economy is in a tough spot, caught between sharply slowing demand in many advanced economies and rising inflation everywhere,” the I.M.F. declared last month in its official World Economic Outlook.