The Dow edged Wednesday to a fresh record in a holiday-shortened session, one day after topping 18,000 points for the first time ever.
The Dow Jones Industrial Average gained 6.04 points (0.03 percent) to 18,030.21, posting its sixth straight gain.
The broad-based S&P 500 snapped a five-day winning streak, falling a scant 0.29 (0.01 percent) to 2,081.88, while the Nasdaq Composite Index rose 8.05 (0.17 percent) to 4,773.47.
US stocks have been on a tear since the Federal Reserve last week kept interest rates low and pledged a cautious approach to raising rates.
Markets had stormed higher early in the day, but weakened in the last minutes of trade. Markets will be closed Thursday for the Christmas holiday.
Briefing.com said volume was light ahead of the holiday, with only 340 million shares changing hands on the New York Stock Exchange floor, compared with the average session of about 826 million.
Biotech stocks, including Gilead Sciences (+2.1 percent) and Celgene (+3.3 percent) rallied after suffering deep declines Tuesday on fears of a price war for pharmaceuticals.
Keurig Green Mountain added 0.8 percent to recover some of its losses from the prior day. On Tuesday, Keurig, which sells specialty coffee and brewing systems, had said it was recalling 7.2 million coffee makers due to a burn hazard.
Petroleum drilling companies, such as Nabors Industries (-2.1 percent) and Transocean (-1.9 percent) suffered as oil prices resumed their downward tilt. Oil companies ExxonMobil, a Dow component, and EOG Resources also fell, 0.9 percent and 2.5 percent, respectively.
Bond prices were mixed. The yield on the 10-year US Treasury held steady at 2.26 percent Tuesday, while the 30-year dipped to 2.83 percent from 2.85 percent Tuesday. Bond prices and yields move inversely.