Comment by AnthonyMouse

> I think that after a certain size, these marketplaces should be regulated to insure due process between the parties.

The solution is not for them to be big and regulated, it's for them not to be so big.

The main thing that would help here is to inhibit vertical integration. For example, suppose people had a legal right to pricing information. Companies like Amazon and eBay would be encouraged to provide an API and have no right to stop anyone from scraping their site for anything it doesn't provide.

Now anyone can make a product search engine that will show you results from any site. You're not stuck with Amazon's gawdawful search. And since anyone can do this, it's easy to enter the market and none of them will have dominance. Conversely, if you want to start a new retailer, or sell your own products directly from your own site, you just submit your site for indexing to the popular product search engines and customers appear. But none of the search engines can destroy you because there are dozens of them and the biggest one is only 15% of the market.

We need more competition. The target of the rules should be to lower barriers to entry.