A European market regulator announced Thursday night that short-selling of stocks in several countries would be temporarily banned in an effort to stop the tailspin in the markets.

The move may put pressure on United States market regulators to ban short sales as well. American bank stocks have been volatile all week as global investors expressed concerns that problems in Europe might cross the ocean.

The European Securities and Markets Authority, a body that coordinates the European Union’s market policies, said in a statement that short sales — negative bets on stocks — would be curtailed in France, Belgium, Italy and Spain effective Friday. There is already a temporary short-sale ban in Greece and Turkey.

“Today some authorities have decided to impose or extend existing short-selling bans in their respective countries,” the authority said. “They have done so either to restrict the benefits that can be achieved from spreading false rumors or to achieve a regulatory level playing field, given the close interlinkage between some E.U. markets.”