E-commerce in the US is growing merely 5.6% if not for the 29% growth of Amazon which raises the overall growth to 16%.

Sales on Amazon in the US are estimated to reach $258.22 billion in 2018, up 29% over 2017, as estimated by eMarketer. This figure is the gross merchandise volume (GMV) and includes direct sales by Amazon itself (also known as first-party or 1P) and the third-party marketplace.

Marketplace sales will make up 68% of the Amazon’s total sales in 2018, and that figure will surpass 70% by 2019. The marketplace will grow 35.6% in 2018, twice the rate of Amazon direct sales’ 17.5% growth. The marketplace is estimated to grow from $175 billion in sales this year to $225 billion in 2019.

Amazon will drive 80% of US e-commerce growth this year. Sales on Amazon are forecasted to grow by $60 billion, while the rest of e-commerce will add $15 billion to its size. As a result e-commerce is growing 16%, but most of that growth happens on Amazon.

Thus by 2019 Amazon will be responsible for more than half of US e-commerce sales.

Network effects of Prime is likely the largest contributor to this. The company has revealed that the Prime membership has grown to one hundred million members worldwide; at least sixty million of those are based in the US - nearly half of households in the country. Research has shown that Prime members are unlikely to price-compare on other shopping websites.