Mark Fiorentino is a former Stripe operator who spent five years across sales support, credit underwriting, finance, corporate development and investor relations before joining Index Ventures, giving him detailed operator-level understanding of payments, risk, and fintech unit economics. He focuses on picks-and-shovels fintech infrastructure that rides on top of large secular shifts, framing opportunities as ETFs on ecosystems rather than standalone point solutions, with particular conviction on Latin American fintech infrastructure like card issuing and cross-border payment rails.

• Deep conviction in the future of fintech infrastructure, particularly regarding cross-border payments and commerce. This includes a belief that the next generation of payment tools will succeed by directly tying revenue generation to cost reduction, as seen in his support for Grain, a platform simplifying foreign exchange for businesses.
• Targeting growth-stage opportunities in AI-native applications and vertical SaaS. He specifically highlights the unique opportunity for AI agents to modernize global trade by reducing capital friction and operational overhead, suggesting that AI will define the next decade of commerce.
• Appreciation for startups that digitize and audit manual, legacy processes in complex industries like logistics. A prime example is his investment in Loop, which he values for its ability to provide a single source of truth for freight invoices, fixing a system where twenty percent of rates historically contained errors.
• Valuing precise financial communication and operational transparency from founders. He explicitly advises entrepreneurs to clearly distinguish between different types of revenue—such as SaaS, payments, and lending—rather than lumping them together, ensuring investors understand the true nature of the business model.
• Bullishness on the potential of emerging markets and international commerce despite economic volatility. He counters the narrative that these markets are too risky by pointing to the massive year-over-year revenue growth of companies like Nubank as proof of the opportunity.
• Admiration for founders who practice radical transparency and retrospection. He praised the team at RevenueCat for their candid approach to building in public, noting that being honest about both wins and losses goes a long way in building trust with investors.