Walgreen Co. reports its fiscal first-quarter results Wednesday as the deadline for its break with pharmacy benefits manager Express Scripts Inc. approaches.

WHAT TO WATCH FOR: Any update on negotiations or litigation between Walgreen, the nation's largest drugstore chain, and Express Scripts, which is one of the biggest pharmacy benefits managers. A contract between the companies expires Dec. 31, and they have been unable to agree on a new one. Walgreen has said Express Scripts is not paying it enough money to fill prescriptions, and Express Scripts says Walgreen wants too much money.

If the companies don't reach a new deal, most people whose pharmacy benefits are handled by Express Scripts won't be able to get their prescriptions filled at Walgreen stores. Walgreen has said it could lose billions of dollars in revenue if it stops doing business with Express Scripts.

Wall Street will also be looking for an update on how the dispute is affecting Walgreen's business. The contract does not expire until the end of 2011, but some shoppers have already taken their business elsewhere. Walgreen said that for November it believes the Express Scripts dispute reduced its revenue from stores open at least a year — a key metric of a retailer's health — by 1.1 percent.

WHY IT MATTERS: Walgreen operated 7,811 stores as of Nov. 30. That means millions of people fill their prescriptions at its stores, and its relationships with pharmacy benefits managers — which pay drugstores to fill prescriptions — has a significant effect on other drugstores. If Walgreen stops doing with Express Scripts, local drugstores and national chains like CVS Caremark Corp. and Rite Aid Corp. could gain large numbers of new shoppers.

WHAT'S EXPECTED: Analysts polled by FactSet expect Walgreen to report a profit of 67 cents per share and $18.22 billion in revenue.

LAST YEAR'S QUARTER: The Deerfield, Ill., company posted a profit of $580 million, or 62 cents per share, as revenue rose to $17.34 billion.