The U.S. Supreme Court gave the country's largest companies a new shield from multibillion-dollar lawsuits, as the justices rejected a bid to sue Wal-Mart Stores Inc. on behalf of more than a million female workers.

The ruling limits the ability of plaintiffs' lawyers to win large awards through a single lawsuit, particularly against employers. It's the second such step this year from the court, which in April said companies can channel customer and employee grievances into arbitration without the possibility of class actions.

The latest decision will have its most direct effect on job-bias cases. Five of the court's nine justices said class-action status is incompatible with a nationwide suit alleging local store managers had too much discretion over hiring and promotion.