Wall Street aims to break even for 2015

Traders will be on watch to see if U.S. stocks can cling to 2015 gains on the final trading day of the year.

The S&P 500 ended Wednesday at 2,063, just 0.2 percent higher on the year, and a little more than 3 percent below the all-time high of 2,134 it reached in May. The Dow, off 117 points Thursday at 17,603, is still negative, down 1.2 percent for the year. But Nasdaq is outperforming, up nearly 7 percent year to date, and it is home to some of the brightest stars in the market.

For next year, Wall Street strategists expect a modest gain for the S&P 500. The average forecast of 14 strategists surveyed by CNBC is 2,213 for year end 2016, a 6.8 percent gain from current levels.