The Marketplace FlywheelWide moat
Amazon (AMZN) — moat facet
Amazon's quiet masterstroke: monetizing millions of other people's businesses — fees on sales, storage, shipping, and now attention.
The third-party marketplace was Amazon's quiet masterstroke, and it is the piece of the business that most fully transformed its economics. Rather than buying and stocking every item itself — an enormously capital-hungry proposition — Amazon opened its storefront to millions of independent1 sellers, invited them to bring the selection, and took a cut of their sales plus fees for advertising and fulfillment. In one stroke it made its selection nearly infinite while shifting much of the inventory risk and capital burden onto others. It is a beautiful arrangement, and it is the reason Amazon can be the 'everything store' without owning everything.
At its heart lies a classic two-sided network effect, and network effects are among the most powerful moats in all of commerce. The customers draw the sellers, because sellers want access to the largest pool of buyers; and the sellers draw the customers, because buyers want the widest possible selection. Each side makes the platform more valuable to the other, and the advantage grows with size rather than eroding — the bigger the marketplace becomes, the more indispensable it becomes to both buyer and seller.
This is precisely why a new marketplace faces such a brutal chicken-and-egg problem. To attract sellers, it needs buyers; to attract buyers, it needs the selection that only sellers provide — and it must somehow conjure both sides at once, from a standing start, while competing against an incumbent that solved the problem long ago and now enjoys the full momentum of a spinning flywheel. Amazon paid the enormous cost of solving that problem years ago; a challenger must pay it all over again, uphill, against a moving target.
The seller services layered on top have quietly become a business of their own, and a lucrative one. Amazon does not merely take a commission on sales; it charges sellers to store and ship their goods through its fulfillment network, and increasingly it charges them to advertise for prominence within its own search results. The company has, in effect, monetized the sellers' entire operations, earning fees whether a given seller thrives or merely survives, and doing so at high margins with little added cost.
That advertising take deserves particular attention, because it has grown into one of Amazon's most profitable activities — $76 billion over the twelve months to June 20262, and growing 26% in the latest quarter3. When millions of sellers compete for the top slots on a search results page that shoppers with wallets already open are scanning, they will pay handsomely for prominence, and Amazon collects that payment as nearly pure profit. It is a toll levied on the sellers' own struggle for visibility, and a striking example of how each of Amazon's moats quietly feeds another.
Widening. Third-party sellers now drive most of Amazon's unit volume, and the marketplace is a classic two-sided network — more sellers bring more selection and lower prices, which bring more buyers, which bring more sellers. On top of that, Amazon increasingly monetizes the sellers themselves through fulfillment fees, advertising, and lending. Each turn of the flywheel adds selection and profit at once. Despite low-price challengers nibbling at the edges, the core network keeps growing denser and more lucrative. Widening.
Seller fees grew faster than Amazon's own online store (+14.6%). Sellers supplied 61% of paid units in the quarter; a falling unit share would say they are leaving for other channels.
- ReportedRather than buying and stocking every item itself — an enormously capital-hungry proposition — Amazon opened its storefront to millions of independent sellers, invited them to bring the selection, and took a cut of their sales plus fees for advertising and fulfillment.Amazon disclosure — third-party sellers account for ~60%+ of units sold (millions of active sellers) — Company-disclosed, ongoing · publ. 2023-2026 · source ↗
- Moat Explorer calcThat advertising take deserves particular attention, because it has grown into one of Amazon's most profitable activities — $76 billion over the twelve months to June 2026, and growing 26% in the latest quarter.Moat Explorer calculation from Amazon's Form 10-K segment and product-line tables (FY2022-FY2025) and the quarterly results releases: AWS share of operating income = AWS operating income / consolidated operating income ($45,606M / $79,975M = 57.0% in 2025; ($14,161M + $16,621M) / ($23,852M + $27,461M) = 60.0% in H1 2026; $16,621M / $27,461M = 60.5% in Q2 2026; $54,681M / $93,712M = 58.3% TTM); AWS share of net sales $128,725M / $716,924M = 18.0%; retail segments' operating income $29,619M + $4,750M = $34,369M on $588,199M = 5.8%; 2022 segment operating income North America -$2,847M, International -$7,746M, AWS $22,841M against a consolidated $12,248M; North America operating margin -$2,847M / $315,880M = -0.9% in 2022; advertising TTM to June 2026 $17,703M + $21,317M + $17,243M + $19,809M = $76,072M — FY2022-Q2 2026 · publ. 2026 · source ↗Method: Moat Explorer calculation from Amazon's filed segment, product-line and supplemental tables; see the source line for each operand.
- ReportedThat advertising take deserves particular attention, because it has grown into one of Amazon's most profitable activities — $76 billion over the twelve months to June 2026, and growing 26% in the latest quarter.Amazon.com, second-quarter 2026 results release (Form 8-K, Exhibit 99.1) — net sales $200.6B (+20%), operating income $27.5B (13.7% margin), AWS sales $42.2B (+37%, fastest growth in 18 quarters, $169B annualized run rate) and operating income $16.6B (39.4% margin, against 32.9% a year earlier), advertising $19.8B (+26%), online stores +15%, third-party seller services +16%, net income $62.6B including $53.4B of non-operating income primarily from investments in Anthropic, TTM operating cash flow $161.4B against net capital purchases $169.0B and free cash flow -$7.6B; AWS AI business and chips business each above a $25B run rate; Trainium commitments from Anthropic and OpenAI; Amazon Leo at nearly 400 satellites, enough to begin initial service this year; Zoox's NHTSA Part 555 exemption to charge for rides; Alexa+ triers signing up for Prime at a nearly 25% higher rate; supplemental table Q1 2025-Q2 2026 (WW shipping cost growth 3%, 6%, 8%, 10%, 14%, 19%; WW paid unit growth 8%, 12%, 11%, 12%, 15%, 17%; seller unit mix 60-62%; North America TTM operating margin 7.4%); Q3 2026 guidance of $197.0-202.0B net sales and $22.5-26.5B operating income, with growth nearly 400 basis points higher excluding Prime Day in both years — Q2 2026 — quarter ended June 30, 2026 · publ. July 30, 2026 · source ↗