The Dow Jones Industrial Average briefly broke through the 10,000 mark in early Tuesday share trading in New York.
It is the first time investors have pushed the index of large, well-established companies above that psychologically-important level in 18 months.
Experts said the markets were cheered by the expectation that officials of the U.S. central bank would leave its key interest rate unchanged when they meet Tuesday afternoon.
The one percent interest rate is a 45-year low, which is credited with helping the U.S. economy expand at its fastest pace in two decades.
The Dow first broke the 10,000 mark in March 1999, and it hit an all-time high of 11,750 in January 2000.
The DJI last hit 10,000 at the end of May 2002.