Amazon.com Inc. said sales from its business-to-business platform hit an annualized rate of $10 billion globally as it adapted its online retail operations for consumers into an international enterprise serving offices, hospitals and factories.

The Seattle-based internet giant launched Amazon Business in the U.S. in 2015 and reached $1 billion in sales a year later. It now operates in eight countries, including Germany, Japan and India. In the U.S., customers include large schools and hospitals, more than half of all Fortune 100 companies as well as local governments.

The marketplace offers hundreds of millions of products from hundreds of thousands of merchants who pay Amazon a commission on each sale, the company said Tuesday in a blog post.

Amazon’s foray into the business-to-business market challenges Staples Inc. and Costco Wholesale Corp., as well as smaller specialty distributors. By 2020, 12.1 percent of that $9.39 trillion market will be online, according to Forrester Research Inc.

Businesses are shifting their supply-shopping online from less efficient methods such as browsing print catalogs, faxing orders and telephoning sales representatives.