In Q1 2027, Mastercard's net revenues grew 6% year-over-year, but purchase volume growth slowed to 3.4% from 5.9% in the prior quarter, leading to a 9% drop in MA stock. American Express (AXP US), Synchrony (SYF US), Capital One (COF US), and Discover (DFS US) all fell more than 10% due to the shift towards stablecoins like USDC on Solana or Ethereum L2s. This shift significantly reduces transaction costs compared to traditional card networks.