CVS Caremark Corp., the Woonsocket-based giant drugstore chain, said yesterday it has renewed about 75 percent of the large customers at its pharmacy-management segment, which handles the drug plans of big employers, locking in business because of the weak economy.

CVS in some cases used lower prices to keep existing customers, Thomas Ryan, company chief executive officer, said at a JP Morgan conference presentation yesterday. Shares of CVS fell the most in more than seven years on Friday after its profit forecast missed some analysts’ estimates because of the reduced contract prices.

The pharmacy-management industry isn’t involved in a price war, Ryan said, and should benefit from the incoming administration of President-elect Barack Obama because of his plans to “look at ways to improve generics,” which are more profitable.

In 2010, fewer customers will be renewing and pricing will be more stable, Ryan said. CVS will buy back shares valued at about $2 billion in the second half of 2009, he said.

“Locking down our clients was the right thing to do in this environment,” Ryan said. “The pharmacy-management business will perform significantly better next year on an operational basis.”

Separately, CVS (CVS:NYSE) yesterday approved an increase in its quarterly dividend to 7.625 cents per common share, payable Feb. 3 to shareholders as of Jan. 23. The increase translates into an annual rate of 30.5 cents per share, up 2.9 cents from the previous rate of 27.6 cents.

CVS rose $1.76, or 7.1 percent, to $26.69 in New York Stock Exchange composite trading. The shares have declined 27 percent in the past year.