The retailer's website has started to display banners ads by third party advertisers at a higher rate, KeyBanc's analyst Ed Yruma wrote in a note obtained by CNBC.
"We believe Walmart recently began intensifying focus on its advertising business," Yruma wrote.
Additionally, Walmart has begun providing more in-depth data to its advertisers, including its in-store and online shopping information.
Shares of Walmart were lower in afternoon trading on Friday.
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