EBay Inc. shares rose as much as 3.8 percent Monday after ChannelAdvisor said the online retailer’s sales increased 28.2 percent in July, led by demand for cars and fixed-price name-brand items.

EBay climbed 3.3 percent to $45.45 at 2:56 p.m. New York time after earlier touching $45.65. ChannelAdvisor said EBay’s July growth from a year earlier was the biggest jump since the industry researcher started tracking the retailer. Sales of fixed-price goods -- those not sold through an auction -- rose 33.1 percent, while EBay Motors posted growth of 36 percent. Sales through auctions fell 1.1 percent from July 2011, ChannelAdvisor said in a blog posting Monday.

EBay is an investor in ChannelAdvisor, according to the blog.