Amgen Inc. said it will buy back as much as $5 billion in common stock under a new stock repurchase authorization plan the company announced Wednesday.

The Thousand Oaks company currently has $1.5 billion remaining under a previous authorization and has about 1.17 billion shares outstanding.

Amgen also raised its 2006 forecast saying it expects earnings of $3.85 to $3.95 a share, up from $3.75 to $3.85 it initially projected when it gave second-quarter results. Analysts, on average, are forecasting earnings of $3.54 per share on revenue of $13.84 billion, according to Thomson First Call.

Shares in Amgen were up 13 cents in trading Wednesday to $69.80.