US AI Fintech Startup Flex Raises $60M To Redefine Finance For Mid-Sized Businesses
2 min read
AI Fintech Funding Alert
December 5, 2025
Series B Led By Portage Ventures Hits $500M Valuation Amid AI Expansion
San Francisco-based Flex, an AI-driven financial technology firm, has secured $60 million in a heavily oversubscribed Series B round led by Portage Ventures. This investment brings the company’s valuation to nearly $500 million and its total equity funding to $105 million. The capital will accelerate development of an AI-first financial platform tailored for mid-sized businesses earning $2–100 million annually, integrating credit services, payments, business cards, cash forecasting, and wealth management tools.
AI Streamlines Back-Office Operations
Flex focuses on mid-market companies—dubbed “jumbo shrimps”—which represent 40% of U.S. payroll but often lack dedicated financial teams. CEO Zaid Rahman describes Flex as an all-in-one solution: “We empower hundreds of thousands of business owners with AI handling credit underwriting, expense management, payments, cash flow analysis, and ERP integration.”
Key features include:
- Credit agents: Live underwriting processes incorporating human checks to reduce error rates.
- Expense/payment agents: Automated systems that boosted payment volume to $3B in the past year.
- Flex Elite card: An upcoming premium consumer card targeting high-net-worth business owners.
Financial experts monitor all AI outputs, addressing industry concerns about scalability highlighted in recent research.
Funding Drives Product and Team Growth
The capital will expand Flex’s AI infrastructure, fuel product development, and grow its team from 80 employees to support client acquisition. Rahman emphasized a focused approach: “We build deep, specialized tools that bridge enterprise-level capabilities with mid-market accessibility.”
Existing investors Sequoia, Lightspeed, and Greenoaks reaffirmed their support, signaling confidence in Flex’s strategy amid rising competition.
$100B+ Opportunity in the Underserved Mid-Market
Mid-sized businesses face fragmented financial tools—relying on manual processes, slow banking services, and limited credit access—despite driving significant economic activity. Flex consolidates these needs into a unified platform, offering cross-border credit, AI-powered financial planning, and support for generational wealth transitions.
Unlike competitors targeting small businesses or consumers, Flex dominates the premium mid-market niche. Payment volume growth underscores early traction, though challenges around AI accuracy and regulation persist. The firm’s hybrid human-AI model aims to balance rapid scaling with compliance.
Flex’s $60 million Series B round marks a milestone in AI’s transformation of B2B finance—positioning automated agents as virtual CFOs for the backbone of the U.S. economy.
