Will Prime Day Rob Amazon's Holiday Sales?, Inc (NASDAQ: AMZN) posted over $10 billion in revenue over the nearly two-day course of Prime Day, its huge annual sale. To put the figure in context, its e-commerce revenue in the second quarter of the year, the most recently reported, was $77 billion. That’s about $800 million a day. The question that will not be answered, perhaps until Amazon announces its fourth-quarter numbers, is whether people who could have bought holiday gifts in November and December bought them on Prime Day instead.

When Prime Day fell on its traditional date in July, the chance it would be an event to buy gifts for the holidays was close to zero. Research from organizations like the National Retail Federation shows that shoppers still start their heavy buying around Thanksgiving, Black Friday, and Cyber Monday. That is when retailers launch their large sales events after stocking up on inventory. Heavy buying stays in place until just before Christmas.

2020 is different. E-commerce has become more prevelant as a means of shopping this year so far. largely due to the spread of COVID-19. Forrester Research expects e-commerce to represent 20% of all holiday sales as total revenue from online sales rises 18% from last year. Bricks-and-mortar sales are expected to rise only 1% for the same period. If the pandemic shutters traditional retailers, the one-in-five ratio of e-commerce to traditional retailers could tip more in the direction of e-commerce.

No one knows today whether retail sales revenue for the holiday will be a zero sum game. If the national pie stays the same as last year, Amazon may be competing with itself, trying to get shoppers who spent money on Prime Day to spend more again in November and December. Prime Day revenue is already greater than Amazon’s Cyber Monday and Black Friday combined. Prime Day this year may have become the day when Prime members did all or most of their holiday shopping. In other words, they may be done.

Amazon has to contend with retailers who have become more sophisticated with their own e-commerce operations each year. Walmart Inc (NYSE: WMT)Target Corp (NYSE: TGT), and Best Buy offered special sales over the course of Prime Day to keep from having their sales decimated. (They may have pulled their own revenue forward from holiday sales as well.)

Prime Day was a wild success. There is no denying it. However, it may cause Amazon’s holiday sales to suffer.