posted solid third-quarter earnings gains and boosted its share buyback program Monday.

The Thousand Oaks, Calif., health insurer said medical membership rose 4% from a year ago to 15.6 million people in the period ended Sept. 30. Specialty membership rose 4.7% to 46.8 million users, backed by growth in the pharmacy benefit management and behavioral health businesses.

For the third quarter, the HMO earned $315 million, or $1.97 a share. That's up from the year-ago $246 million, or $1.63 a share, and 6 cents ahead of the Thomson First Call Wall Street consensus estimate.

Revenue surged to $5.85 billion from $5.05 billion a year earlier.

WellPoint also added 2.7 million shares to its stock buyback plan, giving it the right to buy back as many as 7.5 million shares. Since December 1997, the company has repurchased 30.7 million shares. There are about 156.3 million shares outstanding.

On Monday, WellPoint slipped $1.94 to $88.23.