Despite headlines that Amazon (AMZN) is “eating the retail world,” a new report from Moody’s Investors Service suggests the e-commerce giant may be the weakest of the big retailers.

To be sure, Amazon’s stock continues to soar and spiked roughly 28% since the beginning of the year. It also continues to outpace other retailers in terms of online sales growth, and its recently finalized acquisition of Whole Foods could help it dominate yet another sector.

Still, the new Moody’s report from Charles O’Shea, Janice Hofferber, and Oliver Alcantara points out that Amazon is falling behind in some other key ways.

“Although Amazon’s share price is outperforming retailers, conventional methods of evaluating operating performance, such as operating margin or any profitability measure, suggest that Amazon is actually the weakest of the large retailers, excluding sales growth,” they write.

The Moody’s report continues: “And even based on that measure, one could argue that Amazon has been ‘buying’ sales for the past 15 years, considering profits have not been its primary focus — unlike other retailers.”

Indeed, Amazon posted a 77% drop in quarterly income last month even though its second-quarter revenue was up 25% from the prior year. Meanwhile, despite that jump in sales, Amazon likely won’t overtake the international dominance Walmart (WMT) has already achieved, according to the Moody’s analysts. As Yahoo Finance’s Nicole Sinclair has written, Walmart’s $308 billion in US revenue for 2016 far exceeds Amazon’s $145 billion in US gross merchandise volume, an estimate from Bloomberg Intelligence that includes third-party sales.

“In terms of total revenues, Amazon continues to grow product sales in the mid-teens, which we note is lower than many brick & mortar retailers’ online growth,” the Moody’s report states. “But again, that growth is nowhere near the retailers’ overall profit levels.”

‘Prime membership estimates are seriously overstated’

One reason that investors may remain infatuated with Amazon despite its lack of profitability may be the apparent success of Amazon Prime, a discount membership that encourages consumers to build their retail lives around the Amazon ecosystem.

While one recent study put the estimated number of Prime members at 85 million in the US, the Moody’s report asserts that “Prime membership estimates are seriously overstated” and points out that Amazon has never disclosed the precise number of Prime members.

“Given the company’s incessant push into new markets and products, it’s easy to understand temptations to overestimate. However, when estimates start hitting 85 million, we think it’s time to pause,” the Moody’s report states.