On Tuesday, investors will get the small business optimism index and an important labor market data point.

At 6 a.m. EST, the National Federation of Independent Business releases its index that gauges small business sentiment as of December. It's expected to rise to 99.6, from 98.4 in November.

At 10 a.m., the job openings and labor turnover survey for November is released by the Labor Department, which accounts for the number of monthly job openings.

It's a quiet day on the earnings calendar, with Synnex  (SNX - Get Report) , an IT company, set to release results after the market close.