One Customer, Twenty-Four Percent — Up From SeventeenNarrow moat

ASML (ASML) — moat facet

Roughly €3.1 billion of additional sales to one buyer in twelve months — and a leading edge consolidating into fewer, larger customers.

ASML's largest customer accounted for €7,796.7 million of net sales in 2025, or 23.9% of the total, against €4,682.4 million and 16.6% the year before1. That is roughly €3.1 billion of additional sales to one buyer in twelve months.

Largest customer net sales (EUR M)EUR 4,682M2024EUR 7,797M202516.6% to 23.9% of total net sales in a single year, as the leading edge consolidates.
Roughly EUR 3.1 billion of additional sales to one buyer in twelve months.

ASML does not name its customers, and the filing notes that the ranking of the largest may shift from year to year — a reminder that this is a business where a single fab's construction schedule can reorder the customer list. What the concentration reflects is the leading edge consolidating: as each node becomes more expensive, fewer companies attempt it, and the ones that do buy more from ASML rather than less.

The dependency is real and unusually symmetric. A customer at nearly a quarter of revenue could hurt ASML badly by pausing purchases — but a leading-edge manufacturer that pauses EUV purchases forfeits the next node, which is a worse outcome for it than for ASML. That asymmetry is the whole reason this concentration is tolerable.

Watch the largest customer's percentage alongside its own capital spending announcements. ASML's revenue is a derivative of a handful of capital budgets, and those are published a year in advance by the customers themselves.

Moat trajectory: Narrowing

From €4.68bn and 16.6% to €7.80bn and 23.9% in twelve months. That is a customer relationship deepening fast, driven by a leading edge where fewer companies attempt each node and the ones that do buy more. Symmetric dependence makes it tolerable; the direction still makes it a concentration.

The number that tests this moat
Reported
Largest customer's share of net sales
23.9% — EUR 7,796.7M, from 16.6%

Roughly EUR 3.1 billion of additional sales to one buyer in twelve months, as the leading edge consolidates into fewer companies that each buy more. The dependence is symmetric: a manufacturer that pauses EUV purchases forfeits the next node. Watch this alongside that customer's own capex announcements.

Source: ASML Form 20-F, FY2025 ↗
References
  1. ReportedThe largest customer was EUR 7,796.7M and 23.9% of net sales in 2025 against EUR 4,682.4M and 16.6% in 2024; ASML notes the ranking of largest customers may shift year to year.
    ASML Form 20-F, FY2025 — total net sales to the largest customer amounted to EUR 7,796.7 million, or 23.9% of total net sales in 2025, compared with EUR 4,682.4 million, or 16.6%, in 2024; in 2025, 38.0% of total net sales were made to the two largest customers; while the ranking of the largest customers may shift year to year, sales remain concentrated among a limited group, and the loss of any key customer or a substantial change in their purchasing behaviour could have a material adverse effect; metrology and inspection customers largely overlap with those purchasing lithography systems — FY2025 (ended December 31, 2025) · publ. February 25, 2026 · source ↗
Sources
Generated September 23, 2026