Visa, Mastercard, and Amex Fall 18-23% as Stablecoin Volumes Hit $33 Trillion, Threatening Interchange Fee Model

Visa, Mastercard, and American Express have each retreated 18 to 23% from their all-time highs as investors reprice the existential risk that stablecoin rails pose to the card industry's core interchange fee model, with stablecoin payment volumes reaching $33 trillion in 2025, a 72% year-over-year increase, according to Bloomberg data cited by Forbes [2]. The selloff has unfolded against a backdrop of concrete competitive action: within a single week in March 2026, all three major payment networks and their closest fintech rival made simultaneous structural moves in artificial intelligence agent payment infrastructure, signaling that the contest for the next generation of payment rails has formally begun [2].

The Interchange Fee at Stake

The economic stakes are straightforward. Visa and Mastercard impose interchange fees of 2 to 3% per transaction, a toll that has underpinned decades of network profitability. Stablecoin processing, by contrast, costs fractions of a cent. The combined 2026 aggregate revenue of the three major card networks is projected at $163 billion, with low-teen percentage earnings expansion expected across the sector - forecasts that look increasingly contingent on stablecoin competition failing to penetrate mainstream retail commerce [1].

A February 2026 analysis by Citrini Research introduced a scenario that has clearly unnerved investors: AI agents, programmed to minimize transaction costs, could autonomously identify the 2 to 3% interchange fee and reroute payments through stablecoin rails without human instruction [1]. Morgan Stanley has quantified the opportunity those agents represent, projecting that agentic commerce could account for $385 billion of U.S. online retail by 2030 [2].

Company	Stock from ATH	Forward P/E	Key Stablecoin Move	Investment
Mastercard	-18%	~22x	Acquired BVNK	$1.8B
Visa	-19%	~24x	Card specs for MPP, Visa CLI	Design partner
American Express	-23%	~16x	Defensive positioning	N/A
Stripe	N/A (private)	N/A	Launched MPP with Tempo; acquired Bridge	$1.1B + $500M (Tempo)

Mastercard's $1.8 Billion Bet on BVNK

Mastercard announced its intention to acquire BVNK, a stablecoin infrastructure company, for as much as $1.8 billion, a transaction described as the company's largest-ever crypto acquisition and the most significant stablecoin-related deal on record [1]. The acquisition is designed to establish Mastercard as a bridge between conventional card infrastructure and emerging stablecoin settlement systems.

"A critical, long-term strategic move" that establishes Mastercard as a connector between conventional payment systems and emerging stablecoin infrastructure. - KBW analyst Sanjay Sakhrani [1]

Mastercard's stablecoin ambitions extend well beyond a single acquisition. The company has developed a three-layer stablecoin payments stack that encompasses consumer-facing stablecoin spending through card credentials, stablecoin settlement options for acquiring institutions in the EEMEA region via an expanded partnership with Circle (enabling USDC and EURC settlement), and stablecoin payouts to wallets through a November 2025 partnership with Thunes [3]. Mastercard's Multi-Token Network (MTN) serves as the programmable settlement substrate supporting tokenized value flows across this architecture [3].

Visa's Dual-Track Response: MPP and the CLI

Visa, which processes $17 trillion in annual volume and reports that contactless payments account for 80% of all in-person transaction volume, has taken a two-pronged approach to the stablecoin challenge [1]. Through its crypto division, Visa contributed card-based extension specifications to the Machine Payments Protocol (MPP), the open framework unveiled by Stripe and blockchain partner Tempo that allows AI systems to autonomously purchase services and consolidate micro-transactions into single blockchain-based settlements [2].

Separately, Visa's Crypto Labs introduced Visa CLI in closed beta: a command-line tool that enables AI agents and developer scripts to process card payments directly from a terminal, without API keys or pre-funded accounts, and compatible with both Stripe's x protocol and MPP [2]. Cuy Sheffield, Visa's crypto lead, described agentic commerce as "a once-in-a-lifetime growth opportunity" in a public statement [2].

Visa has also been piloting its Agentic Ready program with more than 20 banks across Europe, while its USDC stablecoin settlement volume reached an annualized $3.5 billion by the end of 2025 [2].

Stripe's MPP and the Race for Infrastructure Control

The most structurally significant development of the week was Stripe's formal launch of MPP alongside Tempo's mainnet, introducing what analysts have characterized as an "OAuth for monetary transactions." Under MPP, an AI agent sets a spending limit and autonomously initiates micropayments for services including data feeds, computing power, and API requests, before consolidating the total into a single on-chain settlement [2].

Tempo, a collaboration between Stripe and venture firm Paradigm, secured $500 million at a $5 billion valuation last October from investors including Thrive Capital and Greenoaks Capital [2]. Paradigm co-founder Matt Huang, who also sits on Stripe's board, serves as Tempo's CEO, a governance structure that reflects the tightly integrated nature of the Stripe-Tempo relationship [2].

Initial MPP partners include Anthropic, OpenAI, DoorDash, Shopify, Revolut, Standard Chartered, Visa, and Mastercard [1][2]. The breadth of that partner list underscores that MPP is designed as an industry standard rather than a proprietary Stripe product, a strategy that positions Stripe to capture margin from infrastructure rather than from processing volume alone [2].

Stripe processed $1.9 trillion in payment volume in 2025 and had previously acquired stablecoin infrastructure firm Bridge for $1.1 billion [1][2]. The Stripe co-founders' 2025 annual letter noted that "stablecoin payments are progressing quietly and inevitably" [2].

American Express Remains on the Defensive

Among the three publicly traded card giants, American Express has suffered the steepest correction at -23% from its all-time high, despite trading at the most conservative valuation of the group at roughly 16 times forward earnings [1]. The company has not announced a comparably offensive stablecoin or agentic payments initiative as of March 24, 2026.

The divergence in valuation multiples - Mastercard at approximately 22 times forward earnings, Visa at 24 times - may partially reflect market credit for those companies' proactive positioning. Citrini Research has noted that AI-driven cost optimization at scale could systematically erode interchange revenue without any deliberate consumer or merchant decision to abandon card networks, simply because autonomous agents will default to the lowest-cost settlement rail available [1].

"AI-driven autonomous agents are starting to engage with the global payments landscape not merely as tools, but as principal entities. The next major player, akin to Google, PayPal, or Stripe, is likely to emerge from the agentic payments ecosystem." - Simon Jones, CEO of Sumvin [2]

Whether Mastercard's BVNK acquisition and Visa's CLI initiative are sufficient to neutralize that structural threat remains the central question for card network investors heading into the second quarter of 2026.