UPI, one of the world's largest real-time payments networks, processed 23.6 billion transactions worth 29.9 trillion rupees (US$313.5 billion) in July, according to official data. Industry executives have long argued that growth in digital payments has become harder to sustain because payment firms earn no fee on UPI transactions, limiting their ability to invest in the ecosystem. An MDR is a fee paid by merchants to banks and payments service providers for processing digital transactions. One proposal would apply charges only to large merchants while keeping UPI payments free for consumers and small businesses, the sources said. The brokerage estimated such a move could create a revenue pool of 50 billion to 100 billion rupees for the payments industry and benefit companies including Paytm and Pine Labs.