For a B2C marketplace business model, like Alibaba or Amazon, there are two metrics that are unique to this sector.

The first is GMV or gross merchandise volume, which is the total sales dollar volume of merchandise transacting through the marketplace during specific period. It is the real top line or where the consumer side of the marketplace is spending. The overall size of the marketplace is a useful measure as a current run rate measure for the company by annualizing the most recent quarter or month. However, GMV is not equal to revenues.

For B2C marketplace companies. Revenue is the portion of GMV that the marketplace takes. Revenue consists of the various fees that the marketplace earns for providing its services. Typically, these are transaction fees based on GMV that is successfully transacted on the marketplace, but they can also include ad revenue, sponsorship and others.

The take rate is the fee charged by a marketplace on a transaction performed by a third party seller or service provider.

The revenue that is reported on a B2C marketplace company's income statement is equal to the take rate times the GMV. Take rates vary between five to 20% for product marketplaces like Amazon or eBay. Whereas service marketplaces like Uber or Airbnb usually charge a higher rate between 15 to 25%. VC fund investors of marketplace businesses would likely evaluate monthly or annual growth of both GMV and revenues to assess scalability and valuation.