Greece, responsible for 0.4 percent of the world economy, nowposes a threat to international prosperity as investors raise betsits days using the euro are numbered.

A Greek departure from the currency would inflict “collateraldamage,” says Pacific Investment Management Co.'s Richard Clarida,a view echoed by economists from Bank of America Merrill Lynch andJPMorgan Chase & Co. At worst, it could spur sovereign defaultsin Europe as well as bank runs, credit crunches and recessions thatmay spark more euro exits.

Global trade and financial ties mean the pain wouldn't beconfined to the euro area. JPMorgan Chase estimates a 1 percentagepoint slump in the euro countries' economy drags down growthelsewhere by 0.7 percentage point. Exporting nations from the U.K.to China would suffer and commodity producer Russia would facefalling oil prices. While the U.S. may fare better, even it wouldfeel echoes similar to the financial infection following thebankruptcy of Lehman Brothers Holdings Inc.