The Dow Jones industrial average edged up 25 points, or 0.2 per cent, to 16,504 Monday.
The Standard & Poor's 500 index was flat at 1,841. The Nasdaq composite slipped two points to 4,154.
With just one more trading day left in 2013, the S&P 500 is on track for an annual gain of 29 per cent, the biggest since 1997. With dividends included, it's up 32 per cent.
Crocs jumped $2.81, or 21 per cent, to $16.14 after the shoe maker said it was getting a $200 million investment from the private equity firm Blackstone.
Trading volume was very low with many investors on vacation.