Amazon.com Inc.’s Prime Day kicks off this week. So does the annual game of guessing just how many billions of dollars the online giant has taken in the summer bargain bonanza. For the sake of its investors, not to mention economists trying to gauge the health of the U.S. consumer, Amazon should release sales figures after the four-day event concludes on Friday, rather than just make vague statements.

Research groups provide estimates before and after the deal deluge, which typically occurs in in July but happens a month earlier this year. Prime Day has become so big, and the fog around the appetite of shoppers is so great, that actual sales data from Amazon would be warmly welcomed.

Data provider eMarketer estimates that Amazon will generate $15.7 billion of U.S. e-commerce sales from the calendar fixture that kicks off on Tuesday, a 7.1% increase on last year.

But eMarketer won’t update its estimate to take account of actual sales until October. Adobe Inc., which also tracks online spending, will release actual sales data from Wednesday, but covering the whole of the U.S. e-commerce business, not just Amazon.

Market research company Numerator will run a live Prime Day Tracker, showing what consumers are buying. Figuring out whether, for example, American families are using an earlier Prime Day to get ahead of back-to-school shopping or are instead reluctant to tie-up their cash for another four weeks, is also useful qualitative information.

Although Prime Day now stretches across the entire market, as other major retailers, including Walmart Inc. and Target Corp, piggyback off the dates to offer their own promotions, Amazon still accounts for the majority of sales. Sky Canaves, principal analyst for retail and ecommerce at eMarketer, estimates that Amazon will capture 60.3% of U.S. e-commerce sales over the four-day period, its highest share of Prime Day sales since 2019. Pulling the event forward forced some of the competition to scramble to get their own special offers ready in time.

The heightened share makes it even more imperative that Amazon releases fast and accurate data. Simply repeating last year’s comment — that Prime Day was the biggest ever, generating record sales — just won’t cut it. In an emailed response to questions, Amazon said that as a public company it discloses its financial performance at its quarterly earnings, including its deal events.

There are precedents for improved disclosure. Amazon rival Shopify Inc. has provided gross sales for the post-Thanksgiving holiday shopping period through its e-commerce platform since 2021. For a decade, British privately owned retailer the John Lewis Partnership published weekly sales for its eponymous department store and supermarket arm Waitrose, although it ceased in 2020 as the retailer’s performance deteriorated. Reporting more detail can sometimes be uncomfortable, but it’s necessary. John Lewis’s weekly updates enabled retail analysts, investors and economists to track the impact of macro factors on food, fashion, home furnishings and electronics sales. Amazon, by contrast, doesn’t release sales data for its October deals event, Black Friday or Cyber Monday.

Even if Amazon were to announce sales data for Prime Day, some triangulation would be needed. For example, last year, Prime Day expanded to four days from the previous two. Figuring out the like-for-like comparison will take a bit of work. The date can move around — as with 2026 — and one year’s figures aren’t that useful: The most helpful data set will only come once Amazon has released it for several consecutive years. But it needs to make a start.

Not only do faster inflation and potentially higher-for-longer central bank interest rates increase the value of any insights into consumer spending, but economy-watchers have been on guard for a possible deterioration in U.S. data quality. U.S. President Donald Trump has personally used his platform to attack the data, and the various statistics bodies have suffered from years of underfunding, a problem that's gotten even more acute recently.

While Amazon looks unlikely to break its Prime Day omerta, we may, for the first time, get more of a window on the metrics. Poonam Goyal, an analyst at Bloomberg Intelligence, told me that Amazon usually reports Prime Day within its third-quarter earnings. This year, it will be included in the second-quarter results. The company may have to say something about the effect on its sales and profits from the calendar shift.

Even so, Amazon is already trumpeting the savings that Prime members can make by clicking on its buy buttons and signing up its the membership program. It should shout about the sales it has generated once parcels have landed on doorsteps too, and in granular detail.

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—With assistance from Jonathan Levin.

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This column reflects the personal views of the author and does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.

Andrea Felsted is a Bloomberg Opinion columnist covering consumer goods and the retail industry. Previously, she was a reporter for the Financial Times.

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