A continent wide downgrade. This will not be the cause of the Euro Zone collapse but it could speed it up quite a bit.
"Standard & Poor's on Monday warned it may carry out an unprecedented mass downgrade on the credit ratings of euro zone countries if EU leaders fail to reach an agreement on how to solve the region's debt crisis in a summit later this week.
S&P placed the ratings of 15 euro zone countries on credit watch negative — including those of top-rated Germany and France, the region's two biggest economies — and said "systemic stresses" are building up as credit conditions tighten in the 17-nation region.
While a credit watch negative typically signals a possible downgrade in no more than three months, S&P said it expects to conclude its review "as soon as possible" following a crucial summit of EU leaders on Friday."