FOSTER CITY, Calif. (AP) — Gilead Sciences says it will spend $11 billion to buy drug developer Pharmasset at a price more than 88 percent over the stock’s latest closing price in a bet on its experimental hepatitis C treatments.

Gilead says it will pay $137 per share in cash for each Pharmasset share. That stock closed at $72.67 on Friday.

Pharmasset said earlier this month it had started late-stage clinical trials of an experimental hepatitis C drug. It also plans two other late-stage trials in 2012.

Hepatitis C is a viral infection that often has no symptoms but which can lead to life-threatening liver damage.

Gilead will pay for the deal with cash on hand, bank debt and senior unsecured notes. It expects the acquisition to close in next year’s first quarter.