I think something along these lines would be great. The problem with Amazon competing in their own marketplace is that there is far too much information asymmetry -- they know about how their marketplace sellers are setting prices and they know the cumulative sales of all items and trends, whereas the marketplace sellers only see their end of things. Amazon then has the ability to just cut those sellers out as it wishes (either through undercutting, making their own Amazon-branded versions, or even just kicking the seller off the platform with no recourse.
This provides Amazon with the ability to do what financial marketplaces are forbidden: front-running, insider trading, etc with their own "stock" of merchandise.
This provides Amazon with the ability to do what financial marketplaces are forbidden: front-running, insider trading, etc with their own "stock" of merchandise.