Marathon Fund Research
Overview
Marathon Fund is a pre-seed and seed-stage venture fund based in San Francisco, CA, founded and managed by Sandy Naidu as a solo General Partner. The fund's brand identity is built around the concept of endurance — backing founders who are committed to building for the long run, much like a marathon runner. With $7M+ in AUM and 50+ investments made, Marathon Fund operates a dual structure: a core fund focused on early-stage startups and a syndicate that participates in later-stage opportunities.
Investment Thesis
Marathon Fund invests in founders building at the intersection of human performance and technology across three core focus areas:
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Health — Longevity, fertility, nutrition, wellness, and performance optimization. The fund backs companies helping people live longer and perform better, from gut microbiome testing to sports nutrition technology.
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Future of Work — AI-native productivity tools, developer platforms, remote collaboration, and workforce evolution. Marathon Fund believes the future of work will be shaped by AI and intelligent software that amplifies human capability.
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Global Mobility — Cross-border infrastructure, immigration technology, and talent movement solutions. This reflects Sandy Naidu's personal perspective as someone who has run marathons across all 50 US states and all 7 continents, giving her a deeply global worldview.
The fund's tagline is "Backing founders with an athlete-like commitment to the long game" — reflecting the belief that endurance and sustained commitment are key founder traits.
Stage Focus & Check Size
Marathon Fund focuses primarily on Pre-Seed investments with selective Seed participation:
- Primary stage: Pre-Seed
- Check size range: $25K–$250K (fund investments)
- Target post-money valuation: Under $10M
- Syndicate check sizes: $250K–$500K for later-stage co-investments
The fund makes very early bets when post-money valuations are below $10M, targeting founder-stage companies with strong conviction. Through its syndicate, Marathon Fund has also participated in growth rounds for companies like Anthropic, Replit, Perplexity, Databricks, Groq, and Crusoe.
Portfolio Highlights
Marathon Fund has backed 50+ companies. Notable portfolio companies include:
Early-Stage Portfolio (Fund Investments):
- Flora Fertility — Fertility and reproductive health technology (Health focus)
- Fuelin — AI-powered personalized nutrition coaching for athletes, with 65K+ downloads across 140+ countries (Health focus)
- Ambient — (Future of Work or Health focus)
- Vitract — Advanced microbiome and gut health testing, serving 1,000+ practitioners (Health focus)
Late-Stage Portfolio (Syndicate Investments):
- Anthropic — AI safety and large language models
- Replit — AI-native developer platform and coding tools
- Perplexity — AI-powered search and answer engine
- Databricks — Unified analytics and AI platform
- Groq — AI inference chips and hardware
- Crusoe — Sustainable AI cloud infrastructure
Top return reported: 20X. Co-investors include a16z Crypto, Tiger Global, Y Combinator, Hustle Fund, and 8VC.
Team
Sandy Naidu — Managing General Partner
Sandy Naidu is a solo GP described as an "operator turned active investor on a mission to transform how women and athletes build." Her professional background spans:
- Shopify — Product/operations experience
- Charles Schwab — Financial services background
- Hustle Fund — Venture capital experience; maintains strong connections (can introduce 10+ contacts)
- a16z Crypto — Crypto/blockchain ecosystem exposure
Sandy is a passionate endurance athlete: she has completed marathons in all 50 US states plus D.C. (October 2016), all 7 continents (January 2016), and all six World Marathon Majors. She achieved a sub-3-hour finish at the Boston Marathon qualifier (December 2017). This athletic identity shapes her investment philosophy around endurance, commitment, and going the distance.
Sandy also runs "The Long Game" newsletter (thelonggame.today), a Substack publication covering investing philosophy, health optimization, and wealth building for founders, operators, and investors.
Community & Ecosystem
Marathon Fund runs three community programs:
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Investor Community — Accredited investors and family offices gain curated deal flow, syndicate opportunities, quarterly portfolio updates, and direct founder connections.
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Chief of Staff Network — A community of operational leaders featuring quarterly in-person dinners in San Francisco, peer mentorship, and exclusive resources.
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The Long Game Newsletter — Educational content on angel investing, startup investment strategies, health performance, and wealth building.
Decision Process
As a solo GP, Sandy Naidu makes all investment decisions independently. This enables fast, conviction-driven decision-making without committee delays. Given the small check sizes ($25K–$250K), decisions are likely made within 1–2 weeks of meeting a founder.
Geographic Focus
Primarily US-based, with San Francisco as headquarters. Sandy's global athletic background and focus on Global Mobility reflect openness to international founders, particularly those working on cross-border and immigration challenges. No explicit geographic restrictions mentioned.
Writing & Public Thesis
Sandy publishes regularly on "The Long Game" (thelonggame.today), covering:
- The Endurance Portfolio — Tax strategy for long-term wealth building
- Angel Investing: From Basics to Becoming a Solo GP — Educational content on early-stage investing
- Health Performance Content — Sleep optimization, nutrition for high performers
- Retirement Capital Playbook — Using retirement accounts (IRA, Solo 401k) for startup investing
Summary Assessment
Marathon Fund is a small but active solo-GP pre-seed fund with a distinctive identity built around endurance and long-term thinking. Sandy Naidu brings an unusual combination of operator experience (Shopify, Schwab), VC apprenticeship (Hustle Fund, a16z crypto), and deep personal conviction around health and performance. The fund's three focus areas — Health, Future of Work, and Global Mobility — are thematically coherent and reflect authentic founder-market fit. With 50+ investments and a top return of 20X, Marathon Fund punches above its weight for a $7M fund. The syndicate's participation in Anthropic, Perplexity, and other top AI companies demonstrates strong network access despite modest fund size.