Mercury vs Flex revenue models
$75M/year Mercury for main street
The key difference is that Flex gets paid when customers actively use credit, while Mercury gets paid largely for holding cash. That gives Flex a revenue engine tied to fuel, repairs, freight purchases, and stretched payment cycles, because every swipe can produce interchange, every carried Net-60 balance can produce interest, and every overseas transaction can add an FX fee. Mercury instead earns mostly from the yield and revenue share generated when startup deposits are swept through partner banks.
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Mercury has described four revenue streams, deposit revenue share from swept balances, interchange from cards, fees on wires and FX, and a share of venture debt economics. By 2024, the business was still driven primarily by interest sharing on roughly $20B of deposits, with interchange and software a smaller piece.
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Flex is almost the inverse model. Its core customer is a cash tight operator with high weekly spend, not a startup sitting on fresh funding. That means monetization is built around card volume and short duration credit, not parked balances, so revenue rises when customers run more operating expense through the card.
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This also changes sensitivity. Mercury is more exposed to rates because falling yields compress deposit monetization. Flex is more exposed to spend volume and repayment behavior, because interchange, APR revenue, and FX fees depend on how often customers use the card and whether they roll payments beyond the free period.
Going forward, more vertical B2B neobanks will look like Flex than Mercury in segments where owners spend heavily and get paid slowly. The winning product in those markets is less a bank account for idle cash, and more a card plus embedded working capital line that sits inside the day to day operating cycle of the business.