New Delhi, Sept. 16 -- A proposal to apply a Merchant Discount Rate (MDR) of 0.02%, capped at Rs.300, to capital market transactions via UPI has sparked an industry-wide debate over who will ultimately bear the financial burden of digital payments-the platforms, market infrastructure providers, or retail investors.

But what would it cost to run an investment app that adds Rs.200 crore to wallets for stock and derivative trading / invested into mutual funds every day?

Ashish Kashyap, founder of investment platform INDmoney, broke down the numbers behind what appears to be a nominal levy at first glance using simple math in a viral LinkedIn post.

While the rate of 0.02% is significantly lower than earlier apprehensions of a 0.40% charge,...