US stock markets will erase gains swiftly-Prechter

NEW YORK May 7 (Reuters) - The Greek debt crisis shows that another deflationary wave of global credit problems is starting, said longtime technical analyst Robert Prechter on Friday.

U.S. stock markets will erase their past six months of gains "in a matter of weeks," said Prechter, who is president of research company Elliott Wave International in Gainesville, Georgia and known for predicting the 1987 stock market crash.

In a telephone interview with Reuters, Prechter also predicted a "dramatic widening" of U.S. corporate bond yield spreads over Treasuries, which he said has already started.

(Reporting by John Parry; Editing by Chizu Nomiyama )