TLDR:AI agents select payment methods by cost and speed, making stablecoin rails a direct threat to card network fees.Stablecoin transaction volume hit $33 trillion in 2025, growing over 70% year over year as adoption accelerates fast.Card fees range from 2% to 3.5% per transaction, while stablecoin transfers settle in seconds at fractions of a cent.Citi projects stablecoin supply could reach $1.9 trillion by 2030, reshaping Treasury markets and traditional banking.AI using stablecoins is emerging as the biggest threat to global payment companies, and financial markets are already responding. Visa fell 4.6%, Mastercard dropped 5.7%, American Express declined 7.2%, and Capital One slid 8.8% in recent trading. The sell-off reflects a growing concern that AI-driven payment systems could permanently undercut the fee-based business models that have defined card networks for decades. The shift is no longer theoretical — adoption data and institutional behavior suggest it is already underway.Why AI and Stablecoins Together Threaten the Payment Industry’s Core BusinessThe threat is not stablecoins alone. The threat is AI choosing stablecoins over legacy payment rails at scale. AI agents do not carry brand preferences or banking relationships. They evaluate speed, cost, and efficiency — then route accordingly. That behavior puts percentage-based card fees directly in the crosshairs.Card payments currently cost merchants between 2% and 3.5% per transaction. Cross-border payments often exceed 4% once currency spreads and intermediary fees are factored in. Stablecoin networks settle the same transactions within seconds, at a fraction of a cent per transfer. For an AI system managing thousands of payments daily, that difference is not a preference — it is a calculation.Bull Theory captured the concern plainly, writing that “AI systems do not choose payment methods based on brand or existing infrastructure. THE BIGGEST THREAT TO GLOBAL PAYMENT COMPANIES IS AI USING STABLECOINS.Visa is down 4.6%.Mastercard is down 5.7%.American Express is down 7.2%.Capital One is down 8.8%.Markets are beginning to price a structural shift. And the concern is simple.AI systems do not… pic.twitter.com/KO7uPJtU6D— Bull Theory (@BullTheoryio) February 24, 2026They automatically select the fastest and cheapest way to settle transactions.” That mechanical decision-making removes the behavioral loyalty that traditional payment networks have long relied on.The scale of what is at stake makes this threat hard to dismiss. B2B payment flows alone exceed $1.6 quadrillion annually. Global remittance fees still average 6.6%, according to World Bank data. Even a partial migration toward stablecoin settlement redirects enormous revenue away from card networks and toward cheaper digital infrastructure.Stablecoin Adoption Is Growing Fast Enough to Accelerate the ThreatThe growth numbers behind stablecoins reinforce why markets are paying attention now. Stablecoin transaction volume reached roughly $33 trillion in 2025, growing more than 70% year over year. Total supply has expanded past $300 billion, compared with approximately $10 billion just a few years ago.Citi estimates stablecoin supply could reach $1.9 trillion by 2030 and potentially $4 trillion under a bullish scenario. At that level, stablecoin issuers could rank among the largest buyers of U.S. Treasury bills globally. That trajectory also puts pressure on banks, which depend on deposits to fund lending activity.Fireblocks research shows nearly half of financial institutions already use stablecoins for payments. More than 80% report readiness to expand that infrastructure further. McKinsey estimates real-world stablecoin payments across payroll, remittances, and business settlement already approach $390 billion annually and are growing rapidly.Even Visa and Mastercard are integrating stablecoin settlement infrastructure behind the scenes — an acknowledgment that the threat is real. Payment networks are not collapsing overnight, but the fee structures that made them profitable are facing a direct challenge from AI systems built to eliminate unnecessary cost at every step. The post AI Using Stablecoins Is the Biggest Threat to Global Payment Companies appeared first on Blockonomi.