Amgen Inc.’s stock may be depressed, but the company’s board believes that makes it a buying opportunity. The board has authorized an additional $5 billion in stock repurchases.

The Thousand Oaks biotech still has $1.5 billion remaining under an earlier $3 billion buyback program authorized in May, the company said in a statement released late Thursday. The total value of Amgen stock outstanding is $64 billion.

“This new authorization reflects Amgen’s confidence in its long-term prospects,” the company said. Buy-backs help control the number of shares outstanding. The company also can use the stock for employee stock options, which are an important part of its compensation.

Amgen shares have been down 26 percent from their 52-week high last October, a few months before safety concerns began surfacing about the company’s top-selling anemia drugs.

Amgen shares were up $1.07, or 2 percent, to $57.02 in midday trading Friday.