The Dow Jones industrial average was up just seven points, or 0.1 per cent, at 15,552 at noon Eastern time (1600 GMT) Friday. It was up 103 points earlier.
The Standard & Poor's 500 index was down two points, or 0.1 per cent, at 1,754. The Nasdaq composite was down 11 points, or 0.3 per cent, at 3,907.
Trading was halted on the Nasdaq Options Market as of 10:36 a.m. Eastern time, according to Nasdaq OMX. Regular stock trading was not affected.
The S&P 500 closed at a record high seven times during October, most recently on Tuesday. It ended October with a gain of 4.5 per cent.