Share it So you want to launch an online retail business. Cool! Let's get started. First you'll need a website and inventory to make an online store. Now you need customers. They're out there, surely, somewhere on the internet. To find them, chances are you're going to have to go through at least one of three giant tech companies: Google, Facebook or Amazon. Together those companies are valued at nearly $4 trillion. All three dominate key features of online commerce and the internet's current infrastructure. EMarketer has called Google and Facebook a "duopoly" in online advertising, together accounting for more than 52% of the market. Amazon, with an expanding advertising arm, has a growing but still much smaller share. For many traditional and online retailers, advertising on Amazon may be a nonstarter, given that they see the e-commerce giant as a competitor. That leaves, to a large degree, Google and Facebook.