A move to launch crypto-based payments by Walmart or Amazon that bypasses the traditional payments system would send shivers through the nation’s banks and card-network giants.

Walmart and Amazon are reportedly exploring their own corporate stablecoins as a customer payment option, which could potentially reduce the billions of dollars the retailers pay in credit transaction fees.

Shares of Visa and Mastercard were sliding Friday after The Wall Street Journal reported that Walmart and Amazon.com, among other merchants, have been considering issuing their own stablecoins to customers,