Fed On Hold Until Late August By John S. McClenahen Perhaps hoping that it would become a self-fulfilling prophecy, Merrill Lynch & Co., New York, for several months has been saying that the Federal Reserve need not raise U. S. short-term interest rates again this year. This week the Federal Open Market Committee (FOMC) in effect confirmed scattered economic data from the last two months and decided to leave the federal funds rate at 6.5%. The FOMC will be on summer vacation in July. But come Aug. 22, the date the powerful monetary panel is next slated to meet, there are no guarantees that the FOMC will not move again, perhaps raising the short-term rate 25 basis points to 6.75%. It all depends on whether the U.S. economy is at -- or under -- a 3.5% annual, inflation-adjusted growth rate, the kind of economic speed limit that many analysts surmise Chairman Alan Greenspan and his colleagues are comfortable with. Between now and late-August six economic indicators bear watching for clues to the Fed's moves. They are: unemployment, consumer price index, housing starts, retail sales, employment costs, and productivity.