Walmart.com may not be Amazon.com but they are one of the giants that can compete. In February of 2019, Walmart took the #3 position as the third-largest US etailer. This report can be found on emarketer.com.
In the report by emarketer.com they show Walmart's ecommerce sales will grow over 33% in 2019.
Ryan Fork from Rigor.com wrote an outstanding article about WalMart.com statistics which pulled from several good sources in 2012. The article includes Industry Benchmarks, Impact of Conversion Rates, Buyer vs. Nonbuyers, and Bounce Rate.
What is interesting about this article is that it dates back to 2012 and the same results on how speed affects conversion still stands today.
See full article here: https://rigor.com/blog/how-walmart-com-correlates-web-performance-to-business-performance