Pending home sales in the U.S. fell by much more than expected in the month of December, according to a report released by the National Association of Realtors on Monday.

NAR said its pending home sales index fell 4.3 percent to 101.7 in December from 106.3 in November. Economists had expected the index to edge down by 0.3 percent.

A pending home sale is one in which a contract was signed but not yet closed. Normally, it takes four to six weeks to close a contracted sale.