The Closed LoopWide moat

American Express (AXP) — moat facet

Amex keeps the whole merchant fee because it owns the card, the network and the merchant contract, and that structure is sturdier than the fee rate it earns.

American Express is issuer, network and acquirer at the same time, and that integration is where the moat starts. It is "the fourth largest general-purpose card network globally based on purchase volume, behind Visa, China UnionPay and Mastercard"1, with network volumes of $1,897.0 billion in 20252. On most of that volume Amex also issued the card and signed the merchant.

Discount revenue ($M)26,167201924,563202130,739202233,416202335,192202437,4012025American Express Forms 10-K FY2019, FY2023, FY2025; 2021 as restated
The merchant fee still grows, just more slowly than the company.

Owning all three parts means Amex keeps the whole merchant discount. In 2025 that was $37,401 million3, about 2.24% of the $1,669.8 billion of billed business on its cards4. There is no interchange fee paid to another bank, and "there are no collectively set interchange rates on the American Express network"5.

It also means Amex knows both ends of every transaction. The company sees what its cardholders buy and where, which is how it can sell merchants marketing and cardholders offers that a network without the issuing relationship could not build.

The price of that integration is scale. Amex says it believes "Visa and Mastercard are larger than we are in most countries based on purchase volume"6, and a closed loop has to sign every merchant and find every cardholder itself. Acceptance, long the weak point, has been growing: more than 190 million merchant locations by September 20267.

The four pages below take the loop apart: the price merchants pay, the spending per card that justifies it, the acceptance that is being bought, and the absence of interchange that protects it.

The loop also gives Amex information a partial network does not have. Because it issues most of the cards and acquires the merchants, it sees who spent, where, and how much, and it uses that to sell merchants marketing and to give cardholders offers. The company describes Global Merchant and Network Services as providing "multi-channel marketing programs and capabilities, services and data analytics"8. That is the part of the loop no rival network can replicate by lowering its price.

The loop has one more feature that matters to investors: it is expensive to leave. A cardholder with a points balance, an annual fee already paid and a history of spending on the card has reasons to stay that are unrelated to the merchant fee, and a merchant who has accepted the card for years faces cardholders who expect it. Both sides of the loop hold each other in place, which is why acceptance has kept growing even as the price has fallen.

Call it a wide structure with a narrowing price. The merchant fee is still the largest revenue line, but its rate has lost 27 basis points since 2013910 and its share of revenue fell from about 60% in 2019 to about 52% in 202511. If discount revenue fell below half of total revenue, the closed loop would have become the smaller part of the business, and the moat would rest more on what cardholders pay than on what merchants pay.

Moat trajectory: Holding steady

Discount revenue $37.4bn in 2025, 51.8% of revenue; rate 2.24% of billed business.

The number that tests this moat
Moat Explorer calc
Discount revenue share of total revenue
51.8% (2025), from 60.1% (2019)

How much of the company still rests on the merchant fee; below half, the cardholder side would carry the moat.

How it's calculated: Discount revenue divided by total revenues net of interest expense: 37,401 / 72,229 (2025); 26,167 / 43,556 (2019).
Source: Moat Explorer calculation from American Express filings ↗
Aspects of the moat
DIG DEEPER 01
Two Point Two Four Percent
American Express still charges merchants a premium, but the premium has lost 27 basis points since 2013 and nothing in the filings suggests it will…
DIG DEEPER 02
Twenty-Five Thousand Dollars a Card
An American Express card carries about $25,000 of purchases a year, and that spending is what merchants pay the premium for.
DIG DEEPER 03
One Hundred and Ninety Million Locations
American Express is buying away its oldest weakness, 20 million merchant locations at a time, and paying for it with a lower average rate.
DIG DEEPER 04
No Interchange to Cap
A closed loop has no interchange fee for a regulator to cap, so the merchant fee survived rules that cut its rivals; the price was losing the network…
⚠ Threats to the moat
⚠ THREAT 01
The Discount Rate Only Goes One Way
The American Express merchant rate has risen in one year out of twelve, and every force acting on it pushes it lower.
⚠ THREAT 02
Visa and Mastercard Are Larger in Most Countries
Amex keeps the whole fee on a network that its own filing says is smaller than Visa's and Mastercard's in most countries.
References
  1. ReportedIt is "the fourth largest general-purpose card network globally based on purchase volume, behind Visa, China UnionPay and Mastercard", with network volumes of $1,897.0 billion in 2025.
    American Express Form 10-K for fiscal 2025 - card metrics: billed business, spending per card, cards-in-force, fees per card and network volumes. — FY2025 · publ. 6 February 2026 · source ↗
  2. ReportedIt is "the fourth largest general-purpose card network globally based on purchase volume, behind Visa, China UnionPay and Mastercard", with network volumes of $1,897.0 billion in 2025.
    American Express Form 10-K for fiscal 2025 - card metrics: billed business, spending per card, cards-in-force, fees per card and network volumes. — FY2025 · publ. 6 February 2026 · source ↗
  3. ReportedIn 2025 that was $37,401 million, about 2.24% of the $1,669.8 billion of billed business on its cards.
    American Express Form 10-K for fiscal 2025 - card metrics: billed business, spending per card, cards-in-force, fees per card and network volumes. — FY2025 · publ. 6 February 2026 · source ↗
  4. ReportedIn 2025 that was $37,401 million, about 2.24% of the $1,669.8 billion of billed business on its cards.
    American Express Form 10-K for fiscal 2025 - card metrics: billed business, spending per card, cards-in-force, fees per card and network volumes. — FY2025 · publ. 6 February 2026 · source ↗
  5. ReportedThere is no interchange fee paid to another bank, and "there are no collectively set interchange rates on the American Express network".
    American Express Form 10-K for fiscal 2015 - the end of the Costco relationship and its share of billed business, loans and cards; the three-party network; average discount rates 2013-2015. — FY2015 · publ. February 2016 · source ↗
  6. ReportedAmex says it believes "Visa and Mastercard are larger than we are in most countries based on purchase volume", and a closed loop has to sign every merchant and find every cardholder itself.
    American Express Form 10-K for fiscal 2025 - Item 1A risk factors, competition and regulation. — FY2025 · publ. 6 February 2026 · source ↗
  7. ReportedAcceptance, long the weak point, has been growing: more than 190 million merchant locations by September 2026.
    American Express release via Business Wire, 28 September 2026 - accepted at more than 190 million merchant locations; locations outside the United States more than doubled in four years. — September 2026 · publ. 28 September 2026 · source ↗
  8. ReportedThe company describes Global Merchant and Network Services as providing "multi-channel marketing programs and capabilities, services and data analytics".
    American Express Form 10-K for fiscal 2025 - reportable segments (Note 23) and revenue and pretax income by region. — FY2025 · publ. 6 February 2026 · source ↗
  9. ReportedThe merchant fee is still the largest revenue line, but its rate has lost 27 basis points since 2013 and its share of revenue fell from about 60% in 2019 to about 52% in 2025.
    American Express Form 10-K for fiscal 2015 - the end of the Costco relationship and its share of billed business, loans and cards; the three-party network; average discount rates 2013-2015. — FY2015 · publ. February 2016 · source ↗
  10. ReportedThe merchant fee is still the largest revenue line, but its rate has lost 27 basis points since 2013 and its share of revenue fell from about 60% in 2019 to about 52% in 2025.
    American Express Form 10-K for fiscal 2025 - card metrics: billed business, spending per card, cards-in-force, fees per card and network volumes. — FY2025 · publ. 6 February 2026 · source ↗
  11. Moat Explorer calcThe merchant fee is still the largest revenue line, but its rate has lost 27 basis points since 2013 and its share of revenue fell from about 60% in 2019 to about 52% in 2025.
    Moat Explorer calculation from American Express's reported figures ($ millions unless stated). Incentives (variable customer engagement costs = Card Member rewards + business development + Card Member services): 2021 11,007 + 3,762 + 1,993 = 16,762; 2022 14,002 + 4,943 + 2,959 = 21,904; 2023 15,367 + 5,657 + 3,968 = 24,992; 2024 16,599 + 5,886 + 4,782 = 27,267; 2025 18,409 + 6,457 + 6,057 = 30,923; Q2 2026 5,051 + 1,755 + 1,949 = 8,755; Q2 2025 7,508. As a share of discount revenue: 16,762 / 24,563 = 68.2%; 21,904 / 30,739 = 71.3%; 24,992 / 33,416 = 74.8%; 27,267 / 35,192 = 77.5%; 30,923 / 37,401 = 82.7%; Q2 2026 8,755 / 10,163 = 86.1%; Q2 2025 7,508 / 9,361 = 80.2%. Discount revenue left after incentives: 24,563 - 16,762 = 7,801; 30,739 - 21,904 = 8,835; 33,416 - 24,992 = 8,424; 35,192 - 27,267 = 7,925; 37,401 - 30,923 = 6,478; Q2 2026 10,163 - 8,755 = 1,408; Q2 2025 9,361 - 7,508 = 1,853. Incentives / total revenue 16,762 / 42,380 = 39.6%; 30,923 / 72,229 = 42.8%. Incentive growth 30,923 / 16,762 - 1 = 84%; 30,923 / 27,267 - 1 = 13.4%. Discount revenue growth 37,401 / 24,563 - 1 = 52%; 37,401 / 35,192 - 1 = 6.3%. Rewards 18,409 / 11,007 - 1 = 67%; rewards / discount revenue 11,007 / 24,563 = 44.8%; 14,002 / 30,739 = 45.6%; 15,367 / 33,416 = 46.0%; 16,599 / 35,192 = 47.2%; 18,409 / 37,401 = 49.2%. Business development 6,457 / 3,762 - 1 = 72%; / discount revenue 3,762 / 24,563 = 15.3%, 6,457 / 37,401 = 17.3%. Card Member services 6,057 / 1,993 = 3.04 times (+204%); 6,057 / 1,392 = 4.35; growth 3,968 / 2,959 - 1 = 34.1%; 4,782 / 3,968 - 1 = 20.5%; 6,057 / 4,782 - 1 = 26.7%; 6,057 / 2,959 = 2.05. Card Member services / net card fees 1,993 / 5,195 = 38%; 3,968 / 7,255 = 55%; 6,057 / 9,993 = 61%; Q2 2026 1,949 / 2,862 = 68%. Membership Rewards liability 16.5 billion / equity 33,474 = 49%; URR +1 point = 4 x 229 = 916. Card fees: 9,993 / 4,042 = 2.47 (+147%); 9,993 / 5,195 - 1 = 92%; growth 6,070 / 5,195 - 1 = 16.8%, 7,255 / 6,070 - 1 = 19.5%, 8,449 / 7,255 - 1 = 16.5%, 9,993 / 8,449 - 1 = 18.3%; added 9,993 - 8,449 = 1,544. Share of revenue 4,042 / 43,556 = 9.3%; 5,195 / 42,380 = 12.3%; 7,255 / 60,515 = 12.0%; 9,993 / 72,229 = 13.8%. Average fee per card 131 / 58 = 2.26; 117 / 103 - 1 = 14%. Proprietary cards 86.6 / 70.3 - 1 = 23%. Marketing 6,252 / 12.5 million new cards = about $500; 6,252 / 1,544 = 4.0. Card fees plus net interest income (9,993 + 17,364) / 72,229 = 38%. Spending per card 23,496 / 20,392 - 1 = 15.2%; 24,059 / 23,496 - 1 = 2.4%; 24,608 / 24,059 - 1 = 2.3%; 25,453 / 24,608 - 1 = 3.4%. Billed business 1,669.8 / 1,070.5 - 1 = 56%; 1,669.8 / 1,550.9 - 1 = 7.7%; 870.7 / 1,070.5 - 1 = -18.7%. Network volumes 1,897.0 / 1,265.7 - 1 = 50%; 1,897.0 - 1,669.8 = 227.2. Merchant rate 2.51% - 2.24% = 0.27 points x 1,669.8 billion = about 4.5 billion; 4.5 / 37.4 = 12%. Pretax income 13,795 - 10,689 = 3,106. Revenue mix 2019: discount 26,167 / 43,556 = 60.1%; net interest income 8,620 / 43,556 = 19.8%; 2025: 37,401 / 72,229 = 51.8%; 17,364 / 72,229 = 24.0%. Net interest income 17,364 / 7,750 = 2.24; 17,364 / 8,620 - 1 = 101%; +100bp +19 / 17,364 = 0.1%. Card Member loans 151,832 / 87,400 - 1 = 74%. Held for sale 2,457 / 151,832 = 1.6%. Revenue 2020 36,087 / 43,556 - 1 = -17%. Deposits 152,488 / 210,300 = 72.5%; 156,973 / 152,488 - 1 = 2.9%. Delta: 13% x 1,669.8 = 217 billion; 8.2 billion / net income 10,833 = 76%; 8.2 / net card fees 9,993 = 82%; 8.2 / 7.4 - 1 = 11%. Other cobrands 26% - 13% = 13% x 1,669.8 = 217; proprietary 74% x 1,669.8 = 1,236. Valuation: market value 206.30 / 254.84 - 1 = -19%; P/E 206.30 / trailing net income 11.446 = 18.0; P/S 206.30 / 75.95 = 2.72; end-2025 254.84 / 10.833 = 23.5; end-2015 68.45 / 5.163 = 13.3; earnings yield 1 / 23.5 = 4.3%. Trailing twelve months to June 2026: revenue 72,229 + 38,544 - 34,823 = 75,950; net income 10,833 + 6,082 - 5,469 = 11,446; EPS 15.38 + 8.81 - 7.71 = 16.48. Diluted shares 696 / 1,003 - 1 = -30.6%. Net income 10,833 / 5,163 = 2.10; EPS 15.38 / 5.05 = 3.05. Berkshire 151.61 million / 675 million = 22.5%; 13F shares 1,149,942 + 149,061,045 + 1,399,713 = 151,610,700, value 388,967,882 + 50,419,898,471 + 473,452,922 = $51.28 billion (30 June 2026). Card balances consumer 144,974 / 218,054 = 66%. Card fees / discount revenue 9,993 / 37,401 = 27% (2025), 4,042 / 26,167 = 15% (2019). Marketing plus incentives 6,252 + 30,923 = 37,175. Provisions / net interest income 5,256 / 17,364 = 30%. Card Member loans growth 139,674 / 125,995 - 1 = 11%; 151,832 / 139,674 - 1 = 9%; billed business 1,550.9 / 1,459.6 - 1 = 6%. Price to book 305.50 / 48.42 = 6.3. Receivables 62,031 / (151,832 + 62,031) = 29%. GMNS Q2 2026 pretax 1,128 / 1,054 - 1 = 7%. Dividend yield 3.80 / 305.50 = 1.2%. Discount revenue at the 2013 rate 2.51% x 1,669.8 = 41.9 billion; each basis point of rate 0.0001 x 1,669.8 billion = 167 million (5bp 835, 10bp 1,670). Merchant locations at the start of 2026 about 190 - 20 = 170 million. Card Member services growth 2021-2025 +204% against net card fees +92%. A 2020-sized fall today: 18.7% x 1,669.8 = about 312 billion. Revenue outside the United States (7,073 + 5,218 + 4,194) / 72,229 = 23%. 2026 revenue guidance 72,229 x 1.10 = 79,452. Segments (2025, $ millions): revenue 34,814 + 16,926 + 13,000 + 7,759 = 72,499; less Corporate and Other 270 = 72,229. Shares of segment revenue: USCS 34,814 / 72,499 = 48.0%; CS 23.3%; ICS 17.9%; GMNS 10.7%. Pretax income 6,810 + 3,668 + 1,603 + 3,968 = 16,049; shares USCS 42.4%, CS 22.9%, ICS 10.0%, GMNS 24.7%. Pretax margins: USCS 6,810 / 34,814 = 19.6% (2020 3,103 / 16,347 = 19.0%; 2021 5,958 / 18,922 = 31.5%; 2022 5,400 / 23,914 = 22.6%; 2023 5,433 / 28,116 = 19.3%; 2024 6,377 / 31,427 = 20.3%); CS 3,668 / 16,926 = 21.7% (2020 1,013 / 9,234 = 11.0%); ICS 1,603 / 13,000 = 12.3% (2020 521 / 6,742 = 7.7%; 2021 929 / 7,435 = 12.5%; 2022 578 / 9,061 = 6.4%; 2023 973 / 10,430 = 9.3%; 2024 1,031 / 11,461 = 9.0%); GMNS 3,968 / 7,759 = 51.1% (2020 1,294 / 4,309 = 30.0%; 2021 1,874 / 5,129 = 36.5%; 2022 2,954 / 6,475 = 45.6%; 2023 3,656 / 7,396 = 49.4%). ICS pretax 1,603 / 1,031 - 1 = 55%. GMNS 2024 excluding the Accertify gain 4,398 - 531 = 3,867; 3,968 / 3,867 - 1 = 2.6%. Revenue 2020 to 2025: USCS 34,814 / 16,347 = 2.13; CS 16,926 / 9,234 = 1.83; ICS 13,000 / 6,742 = 1.93; GMNS 7,759 / 4,309 = 1.80. 2020 segment total 16,347 + 9,234 + 6,742 + 4,309 = 36,632; USCS share 16,347 / 36,632 = 44.6%. USCS Q2 2026 pretax 2,065 / 1,676 - 1 = 23%. Regions 2025: pretax 13,054 + 1,255 + 831 + 907 = 16,047; United States 13,054 / 16,047 = 81%; 13,054 / consolidated 13,795 = 95%; outside the United States (1,255 + 831 + 907) / 16,047 = 19%; revenue 56,015 / 72,229 = 78% - the incentive lines (rewards, business development, Card Member services) against discount revenue and card fees. — 2013-2026 · publ. September 2026 · source ↗
    Method: Arithmetic on figures reported in American Express's Forms 10-K, 10-Q, earnings releases and statistical supplements, Delta Air Lines' Form 10-K and market data; operands shown in the source line.
Sources
Generated September 28, 2026