Amazon.com

(AMZN) - Get Report

was down 2.6% in late morning after

Lehman Brothers

in a commentary said the road ahead is "challenging" for the online retailer.

Lehman said Amazon's growth is decelerating, and what growth there is comes from the "wrong segments" -- international and early-stage businesses. Because these segments require higher marketing costs and produce lower margins, Lehman finds this "worrisome."

The brokerage rates Amazon market perform.