Amazon Seller Briefing: September 17, 2026

Amazon confirmed on its Seller Forums that Prime Big Deal Days deal submissions close September 22, 2026, correcting this publication's earlier unverified label. Deal prices are excluded from Black Friday lookbacks. Also: a reported plan for 1,000+ same-day sites by 2031, and banned mercury creams found on Amazon.

Published September 17, 2026 · Seller Signal daily briefing

Good morning, sellers! Welcome to September 17, 2026's edition. Today: a correction — Amazon did extend Prime Big Deal Days deal submissions to September 22, and this publication was wrong to call it unverified — plus a reported plan for more than 1,000 same-day sites, and a Reuters finding that puts skin-lightening listings under a spotlight. Let's dive in…

Data gathered at 6:05 AM ET, September 17, 2026.

Amazon published no new Seller Central policy, fee or Amazon Ads announcement that could be verified in the past 24-48 hours. The lead item is a correction to this publication's own reporting.

1. Top Story of the Day

Correction: Amazon extended Prime Big Deal Days deal submissions to September 22

What happened: On September 8, 2026, Amazon's staff account News_Amazon posted "Prime Big Deal Days deals deadline extended" to the Amazon Seller Forums: "The deal sourcing window for Prime Big Deal Days has been extended to September 22, 2026, giving you more time to prepare for this sales event." The previous close was September 8. Eligible types are Best Deals, Lightning Deals, Prime Exclusive Discounts and coupons. EcomCrew reported the extension on September 16. The event runs October 6-7.

The same post states: "Prime Big Deal Days promotional prices are excluded from the 30-day and 60-day lookback window and will not affect the maximum deal price required for Black Friday Week and Cyber Monday deals."

Why it matters: On September 15 this publication labelled the September 22 extension Unverified and said no Seller Central or Seller Forums post confirming it could be found. That was wrong. The Amazon post existed and was a week old. Any seller who skipped submissions on the strength of that label still has until September 22 — five days from today.

Expert take: The lookback exclusion is the more valuable half of the post. It means a deep Prime Big Deal Days price does not lower the ceiling your Black Friday Week and Cyber Monday deals must beat, so the October event does not have to be priced defensively. Inventory is the constraint that did not move: the final FBA inbound deadline for Prime Big Deal Days on Amazon-optimized shipment splits was September 16. A deal submitted this week has to be served from stock already on hand or inbound. The post also points sellers with more than 90 days of supply, or inventory aged over 180 days, to Amazon Outlet during the event.

Action items:

If you held back submissions after September 15, check eligible ASINs in your Deals dashboard and submit by September 22.
Size each deal against units already on hand or inbound, not against new shipments.
List ASINs with more than 90 days of supply or inventory aged over 180 days on Amazon Outlet around the event.

Sources: Amazon Seller Forums, September 8, 2026; EcomCrew, September 16, 2026.

2. Marketplace Opportunities & Threats

Amazon's reported Project Mercury would put same-day sites within 10 miles of 80% of Prime members

Setup: Business Insider reported on September 16, 2026, from internal Amazon planning documents, that Project Mercury targets more than 1,000 US same-day fulfillment facilities by 2031, up from about 85 today, placing one within 10 miles of 80% of US Prime members. This is a report, not an announcement. An Amazon spokesperson said the internal projections are "preliminary and could change," while the company is "focused on delivering faster for customers, and the expansion of our same-day delivery network is playing a big role in that."

Math: About 85 to more than 1,000 sites is roughly a twelvefold increase. Same-day facilities stock about 90,000 popular items each; a smaller Orbital design covers about 100,000 square feet and processes about 75,000 same-day and perishable units a day. The documents put US same-day capacity spending at $6.8 billion this year and next, project $7.1 billion in economic value over a decade and positive cash flow by 2030, and forecast same-day at 28% of Amazon-fulfilled volume in 2029 and 50% by 2035.

Who this fits: FBA sellers in groceries, household supplies, medicine and other frequently purchased goods — the categories the plan focuses on.

Window: A planning horizon to 2031, on figures Amazon calls preliminary.

Execute: Nothing to act on this quarter. The strategic point is selectivity: 90,000 items per site is a small slice of the catalog, so same-day placement becomes a competitive position rather than a default. EcomCrew's read is that "national in-stock status may tell you less than regional availability." It is the long-range version of the Sub Same Day per-unit bidding covered here September 11 — watch whether bidding scales with the network. (PYMNTS; EcomCrew)

3. Compliance & Account Health Alerts

Reuters finds banned mercury skin bleachers still listed on Amazon, Temu and TikTok Shop

Reuters reported on September 16, 2026 that more than 20 banned mercury-containing skin-bleaching products from public banned lists were available on the US marketplaces of Amazon, Temu and TikTok Shop, and on Amazon's third-party marketplaces in France, India, the UAE and Belgium, as of September 1. The FDA limits mercury in cosmetics to no more than 1 part per million and published a list of mercury-containing skin-lightening creams in May. France issued a recall notice for one product on August 28; it was still on Amazon's Belgian site on August 31. Amazon said it prohibits the sale of these products and is taking steps to remove them and act against their sellers.

Consequence: Amazon says removals are under way. If they run on keywords, legitimate sellers of skin-lightening, whitening or brightening products are the ones most likely to be caught alongside the banned listings. Keep ingredient lists and test documentation ready to answer a suppression or appeal quickly. (Reuters via CP24)

4. Seller Community Pulse

Unavailable — no verified community signal from the past 24-48 hours.

5. Looking Ahead

September 18: CBP may begin voiding Importer of Record numbers over inaccurate Form 5106 data.
September 21: TikTok Shop EU-UK cross-border pilot opens; full launch October 19.
September 22: Prime Big Deal Days deal submissions close.
September 22-24: Amazon Accelerate 2026 in Seattle; CBP Entry Type 13 test begins in ACE September 22.
September 25: FTC comment deadline on its proposed enforcement policy statement on personalized pricing.
September 28-30: Amazon unBoxed 2026 at Moscone West, San Francisco.
September 30: Business Hour Delivery Rate takes effect for US seller-fulfilled Amazon Business orders.
October 6-7: Prime Big Deal Days in 22 countries.
October 14, 21 and 28: BFCM inbound deadlines — AWD, minimal, Amazon-optimized splits.
October 15: FBA holiday peak fulfillment fees begin, averaging $0.32 per unit through January 14, 2027.
October 20: Black Friday Week and Cyber Monday deal submission closes.
November 2: Commercial liability insurance changes take effect for 11 enhanced-safety categories.

All dates 2026 unless stated; Q4 deadlines per Amazon Seller Forums.