Herbalife Ltd. shares soared after documents revealed corporate raider Carl Icahn's huge stake in the Los Angeles-based maker of nutritional foods and supplements.
Shortly after the opening bell on Wall Street, Herbalife shares added $4.72, or 12.3%, to $42.99.
A regulatory filing Thursday showed Icahn has paid $214 million for 14 million Herbalife shares, or 13% of the company.
Icahn previously would not disclose whether he had invested in the company. The storied billionaire investor recently squared off, on live television, with fellow New York hedge fund manager Bill Ackman, chief executive of Pershing Square Capital Management.
On Dec. 20, Ackman accused Herbalife of being a pyramid scheme that defrauds distributors of its products. He announced a $1-billion "short" against the company, a massive bet that its stock will fall.
Herbalife shares plunged after Ackman's presentation. The company launched a public-relations counter-attack and accelerated a share buy-back. With Friday's pop in Herbalife stock, the company's shares were trading slightly higher than they were before Ackman's presentation.