Contracts to buy U.S. previously owned homes fell unexpectedly in November as limited housing stock and lofty prices crimped activity, and the explosion of new coronavirus cases from the fast-spreading Omicron variant poses a risk to the housing market headed into 2022, a trade group said on Wednesday. The National Association of Realtors (NAR) said its Pending Home Sales Index, based on signed contracts, fell 2.2 percent last month to 122.4. Pending home sales were lower in all four regions. Economists polled by Reuters had forecast contracts, which typically become final sales after a month or two, would rise 0.5 percent in November. Pending home sales dropped 2.7 percent in November on a year-on-year basis. Limited inventory has led to double-digit growth in home prices. “There was less pending home sales action this time around, which I would ascribe to low housing supply, but also to buyers being hesitant about …