Stock in Rite Aid Corporation is tumbling today following a dismal earnings update by the company. On Thursday Rite Aid released sales results for May and updated its quarterly and yearly earnings estimates, previewing a year of worse-than-expected earnings.

Rite Aid reported that its front-end same store sales for the five weeks ending on May 31 increased just 0.5% over the same month one year ago. Pharmacy same store sales were up 5% and overall same store sales were up 3.5%. Rite Aid drugstore sales were up 2.5% for the month, hitting $2.484 billion.

For the quarter so far, overall same-store sales increased 3.1% and pharmacy same store sales increased 4.6% over the same 13-week period last year. However, front-end same store sales have not increased, remaining flat for the quarter. Drugstore sales for the quarter so far are up 2.6% to $6.425 billion.

Despite the rise in sales, Rite Aid’s preliminary quarterly results show that the company expects to report between $35 million and $45 million in net income, earning $0.04 per share. The company also expects its quarterly adjusted EBITDA to fall behind that of the same quarter last year. Rite Aid is blaming this decline on “higher-than-expected drug costs” due to delayed price reductions among generic pharmaceuticals and a “greater-than-expected reduction in reimbursement rates.” The company is scheduled to release its final quarterly results on June 19.

Based on these quarterly earnings estimates, Rite Aid revised down its total-year financial guidance. The company now estimates yearly adjusted EBITDA to come in between $1.275 billion and $1.35 billion. Rite Aid now expects to take in between $298 million and $408 million in net income for the year with a corresponding income per share of between $0.30 and $0.40.

The earnings update came as a disappointment to investors who had been expecting Rite Aid to bring in closer to $0.40 per share in income for the year. With $0.40 now closer to the high end of the company’s estimates, Rite Aid could have a hard time satisfying investor expectations in the coming quarters.