The Nasdaq composite eked out a record close on Wednesday, led by gains in Amazon.
The tech-heavy index closed 0.1 percent higher at 6,867.36 as Amazon gained more than 1 percent. Amazon shares rose after CNBC reported the company's cloud business is about to announce a huge health-care deal with Cerner, one of the largest health technology companies in the world.
The Nasdaq has now posted record closes in back-to-back sessions; it also hit an intraday high on Wednesday.
The S&P 500 and Dow Jones industrial average, meanwhile, finished lower after Federal Reserve expresses concern about the impact of the market's sharp rise on the economy in a summary of its previous meeting.
The Dow declined 64.65 points to close at 23,526.18, with DowDuPont declining 0.9 percent to lead decliners.
The S&P 500 fell 0.1 percent to 2,597.08, with financials and real estate as the worst-performing sectors. HP Enterprise was the worst-performing stock in the index.