The U.S. futures industry faced another potential setback Monday after a midsize broker froze client accounts, disclosed that its founder had been hospitalized following a suicide attempt and faced closure after being accused of misstating financial records.

Late Monday, the National Futures Association, the futures industry's self-regulatory body, said it has taken an emergency enforcement action against broker PFGBest's parent company, Peregrine Financial Group Inc., as well as a unit, Peregrine Asset Management Inc. Under...