More people are shopping at Whole Foods Market stores since the retailer lowered its prices, and Walmart shoppers account for the biggest share of new foot traffic.

On Oct. 3, New York-based Thasos Group, a data intelligence firm that analyzes cell phone location information, published a report, “Competitive Impact of Lower Prices at Whole Foods,” that analyzes changes in foot traffic since online giant Amazon bought Whole Foods and subsequently lowered prices.

Foot traffic to Whole Foods stores increased 17 percent year-over-year the week ending Aug. 28, the week the price reductions began. By the week ending Sept. 16, traffic was still up, but only by 4% compared to the year before.

Regular Walmart customers accounted for 24 percent of Whole Foods’ new customers in the first week prices went down, according to the report. Walmart was followed by Kroger (16 percent), Costco (15 percent) and Target (11 percent).

Among Whole Foods’ competitors, Trader Joe’s made up 10 percent of new customers and Sprouts 8 percent.

New Whole Foods customers overwhelmingly belong to the same upper income demographic as the retailer’s traditional customer base, according to Thasos Group.