Real estate stocks are selling off across the board as investors continue to worry the recovery in commercial real estate will be sidetracked by global malaise.

Among the biggest losers are apartment operator AvalonBay Communities, which fell 3.49% to $112.91, and shopping center landord Kimco Realty, which dropped 3% to $14.36.

REITs were the worst performers in the S&P 500 Index, while broader equity indexes were relatively flat.

It's a bit unusual for REITs to react this negatively when the broader market is hanging in there," said Rich Moore, an analyst at RBC Capital Markets.

Jim Sullivan, a managing director of REIT research at Green Street Advisors, said Wednesday's declines reflect concerns among investors that Europe's mounting debt crisis could filter down to hurt U.S. credit markets.