flex
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Sam O'Keefe
Sam O'Keefe is the co-founder and CEO of Flex, the San Francisco fintech often called 'Stripe for HSA/FSA payments.' Flex lets health and wellness brands accept the roughly $150 billion of tax-advantaged health-account money that Americans leave sitting unused every year, turning a confusing benefits process into a one-tap checkout. A two-time Y Combinator founder who previously built fraud and risk software at Unit21 and led startup programs at Google, O'Keefe raised a $15M Series A in September 2025 to make 'pay with HSA/FSA' as ordinary at checkout as PayPal.
Hadi Solh
Hadi Solh is the Co-Founder of Flex, an AI-native finance super app for mid-market business owners, and Managing Partner at Atmos Ventures, a deep-technology venture capital firm. Drawing on 20+ years across Goldman Sachs, McKinsey, and Credit Suisse, he co-built Flex from a construction-industry credit card into a $490M+ funded platform processing $3B+ in annualized payments, serving business owners who power 40% of US payroll. Based in Dubai, he also sits on the boards of Oxford Ionics (quantum computing) and Nethone (cybersecurity).
Zaid Rahman
Zaid Rahman is the founder and CEO of Flex, an AI-native private bank and finance super app targeting mid-market business owners with $3M-$100M in revenue. A Thiel Fellow who left Columbia University to build companies, he previously founded Volley (an AI knowledge startup backed by JPMorgan and Zuckerberg Ventures) and an EdTech platform that was acquired. Inspired by watching his father's Dubai construction business nearly collapse due to a payment default, he co-founded Flex in 2022 to build the all-in-one financial platform that mid-market owners never had. Flex has raised $490.5M in total funding, reached $3B in annualized TPV, and became the first US fintech to launch a Visa Infinite Business credit card.