Amid harsh weather that battered much of the U.S., signed contracts to buy existing homes held steady last month, according to the National Association of Realtors.
The nearly-flat reading caught economists by surprise.
Pending home sales edged up 0.1 percent to 95.0 in January, disappointing analysts who had expected sales to gain 2.0 percent, according to a consensus estimate from Reuters.
The index's reading remained 9.0 percent below January 2013. December's level was upwardly revised in December to 94.9.
"Ongoing disruptive weather patterns in much of the U.S. inhibited home shopping," said Lawrence Yun, NAR chief economist. "Limited inventory also is playing a role, especially in the West, while credit remains tight and affordability isn't as favorable as it was a year ago."
These signed contracts are an indicator of sales in February and March.
Among the index's four regions, the South and Northeast saw gains, which were offset by declines in the West and Midwest.
Weakness in existing home sales is expected in the first quarter, while limited inventory continues to boost prices. Around the middle part of the year, this pace should pick up.
"Increasingnew home construction can quickly solve two problems, producing more inventoryand taming price growth," Yun said.
—By CNBC's Katie Little. Follow her on Twitter @KatieLittle