Senator Calls for Investigation of Herbalife

Company has been accused of running a pyramid scheme

Sen. Edward J. Markey is urging federal regulators to investigate the business practices of Herbalife Ltd., making him the most prominent figure yet to express concern about the Los Angeles maker of nutrition and personal care products.

Herbalife shares were down about 12% Thursday morning on reports of Markey's intervention.

The Massachusetts Democrat asked the Securities and Exchange Commission and Federal Trade Commission to investigate Herbalife, saying he had "serious questions" about the way the company pays its independent sales staff.