Drugstore operator Walgreen Co. says its fiscal second-quarter earnings fell almost 8 percent due in part to its decision to leave the Express Scripts pharmacy network and a slow flu season.

The nation's largest drugstore chain says its net income fell to $683 million, or 78 cents per share, in the three months that ended Feb. 29. That is down from $739 million, or 80 cents per share, a year ago.

Revenue climbed less than 1 percent to $18.65 billion.

Analysts forecast earnings of 77 cents per share on $18.57 billion in revenue.

Its shares climbed $1.25, or 3.6 percent, to $35.62 in premarket trading Tuesday.

Express Scripts is a pharmacy benefits manager that paid Walgreen to fill prescriptions. The companies let a contract between them expire at the end of last year.