The broad-market gauge pushed back above 2,000, the milestone it closed above for the first time on Tuesday, to finish at 2,003.36, up 6.62 points (0.33 percent) for the day.
The blue-chip Dow Jones Industrial Average added 18.75 points (0.11 percent) to 17,098.32, while the Nasdaq Composite gained 22.58 (0.50 percent) to 4,580.27, its best level in 14 years.