Affirm disclosed that 39% of its transactions carry zero interest because merchants foot the bill, a model that's proving more profitable than traditional consumer-paid interest structures. Revenue growth exceeded transaction volume growth in recent periods, driven by what the company calls "improved monetization and higher revenue per transaction."
The merchant subsidy approach solves a core BNPL problem: balancing consumer affordability with platform profitability. Merchants pay Affirm to offer interest-free installments, betting that higher conversion rates and basket sizes offset the subsidy cost. Affirm's AI determines optimal subsidy levels by merchant category, transaction size, and consumer credit profile.
Credit quality remains stable across the shift. Affirm reported that "repayment curves remain solid" and sees no signs consumers are struggling with payments. Default rates and delinquency metrics for personal loans, auto financing, and point-of-sale credit "remained in line with expectations," suggesting merchant-subsidized loans don't attract riskier borrowers.
Customer retention hits 96%, with nearly all transactions coming from existing users. This repeat rate indicates the merchant subsidy model creates sticky consumer behavior—shoppers return to merchants offering Affirm's zero-interest terms rather than switching to competitors or paying cash.
The data points to a sustainable competitive moat. Traditional credit cards can't easily replicate merchant-specific subsidy optimization without rebuilding their economics. Other BNPL platforms lack Affirm's scale to train AI models on subsidy effectiveness across diverse merchant categories.
The model's sustainability hinges on whether merchants see ROI from subsidies. If Affirm's AI accurately targets subsidies to transactions that wouldn't occur otherwise—rather than subsidizing purchases consumers would make anyway—merchants gain incremental revenue that justifies the cost. Early indicators suggest this works: revenue growing faster than volume means Affirm extracts more value per transaction without losing merchant partnerships.
The shift challenges assumptions that BNPL profitability requires charging consumers interest. Affirm's numbers suggest the opposite: merchant subsidies may offer better unit economics by reducing consumer acquisition costs and defaults while increasing transaction frequency. The 75% confidence in this hypothesis reflects strong correlational evidence but limited public data on long-term merchant retention tied specifically to subsidy programs.