JERUSALEM — Teva Pharmaceutical Industries Ltd., the world’s largest generic drugmaker, on Thursday said it would lay off over a quarter of its workforce as part of a global restructuring meant to salvage its ailing business.

Teva said 14,000 workers would be let go. The cuts will be scattered across Teva’s global operations and will occur over the next two years.

The announcement marked a stunning setback for a company seen as a national source of pride in Israel. With roots going back more than a century, Teva has grown into a major global player over the past 40 years with a series of acquisitions, and by developing original drugs and leading the move toward cost-saving generics.

Teva’s most famous product is Copaxone, a treatment for multiple sclerosis, and it recently became one of two companies offering a generic version of the blockbuster drug Viagra.

In a letter to employees, Chief Executive Kare Schultz said the restructuring is “crucial to restoring our financial security and stabilizing our business.”

Teva’s bottom line has been hit by the expiration of patents on Copaxone, pricing pressure on its core generics business and a $35 billion debt load taken on in its acquisition of the generics business of Allergan.

Teva’s U.S.-traded stock has skidded nearly 60 percent this year. But after the announcement, its shares were sharply higher Thursday, up 14 percent at $17.98 after trading opened on Wall Street.