Stocks were flat, failing to hold onto a rebound off a steep two-day decline as investors are looking ahead to Friday's payroll report, Reuters reports.

"While stocks are flat, any bias will be to the downside given all the nervousness ahead of the report tomorrow, a big piece of data at a time when the Fed is very data-driven," said Leo Grohowski, chief investment officer at BNY Mellon Wealth Management in New York.