Amazon (NASDAQ: AMZN) has said that it will add 100,000 new small businesses to its selling platform in the coming year, a 20% increase over the half-million that currently sell there, while also spending $18 billion in 2020 to help them reach more customers and grow sales. The e-commerce giant told the U.S.-based small- and medium-size businesses attending its virtual Amazon Accelerate summit that it has already released more than 135 tools and services this year to help sellers manage their Amazon businesses. Third-party sellers have long grumbled about how Amazon treats them.