Wall Street will be looking for insight into the changing pharmacy benefits management industry when CVS Caremark Corp. reports its third-quarter results Thursday.

WHAT TO WATCH FOR: Comments on the proposed merger of Express Scripts Inc. and Medco Health Solutions Inc., the two biggest competitors to the Caremark pharmacy benefits management business.

Express Scripts agreed to buy Medco in July for $29.1 billion. Caremark is also at the beginning of a new contract with Aetna Inc., and it has recently reported some significant new contracts and acquisitions.

Meanwhile, Americans have cut back on medication use because of the weak economy, which hurts both drugstores and PBMs. Pharmacy benefits managers run prescription drug plans and use large purchasing power to negotiate lower drug prices. They make their money by reducing costs for health plan sponsors and members.

WHY IT MATTERS: The Woonsocket, R.I., company is one of the biggest pharmacy benefits management companies, with market share about equal to Express Scripts and Medco. But if Express Scripts is able to buy Medco the resulting company would be far larger than Caremark, and the the new Express Scripts would handle about 30 percent of all U.S. prescriptions. That might give it the ability to negotiate bigger discounts for its clients than Caremark, a huge competitive advantage.

However CVS Caremark would still have a great deal of purchasing power. CVS the second-largest chain of drugstores in the U.S. with around 7,200 locations.

WHAT'S EXPECTED: Analysts forecast a profit of 67 cents per share on $26.77 billion in revenue, according to FactSet.

LAST YEAR'S QUARTER: In the third quarter of 2010, CVS Caremark reported a profit of $809 million, or 59 cents per share. Excluding acquisition costs and other items, the company said it earned 65 cents per share. Its revenue declined to $23.88 billion.