The stock of Zillow, a real estate website, jumped 79 percent in its first day of trading. Zillow's initial public offering priced at $20 late Tuesday.
The Dow Jones industrial average fell 16 points, or 0.1 percent, to close at 12,572.
The S&P 500 index dropped less than 1 point to 1,326. The Nasdaq fell 12 points, or 0.4 percent, to 2,814.
Rising stocks outpaced falling ones by a small margin on the New York Stock Exchange. Trading volume was below average.