Shares of Rite Aid ( RAD) slid 5% Friday after Goldman Sachs downgraded the drugstore chain to sell from neutral. The firm noted valuation concerns and said the company could face challenges with the integration of Eckerd and Brooks chains. The risks associated with the deal could thus weigh on shares in 2007, Goldman said. The downgrade comes a day after Rite Aid shareholders approved the roughly $3 billion acquisition of Eckerd and Brooks from Canada's Jean Coutu Group. The purchase will give the company 1,858 more drugstores and six distribution centers, bringing its total store count to over 5,000. Shares of Rite Aid recently were down 33 cents to $5.81 on heavier-than-average volume.