Rebel Fund Research
Investment Thesis
Rebel Fund is a San Francisco venture fund that invests only in Y Combinator-backed startups. It aims to back the top 10% of YC startups, which it describes as the top 0.06% of all YC applicants. The pitch is that YC is the strongest early-stage filter in the world, with 100+ unicorns and more than $1.3T in portfolio company value, and that a diversified portfolio of the best YC companies is statistically powered to outperform. Rebel says it has unusual access to top YC startups, with a nearly 100% deal win rate, typically before Demo Day.
Data-Driven Selection
Rebel maintains what it calls the most comprehensive database of YC startups, founders and outcomes outside YC itself, with millions of data points across every batch. It trains a proprietary machine-learning model, Rebel Theorem 5.0, to predict YC startup success before Demo Day and uses it to validate and screen investments. Managing Partner Jared Heyman publishes data-driven essays on Medium covering what predicts YC success, why to ignore press picks at Demo Day, batch-level trends for S26 (a swing back toward atoms and hardware), and whether the most expensive YC startups are worth the premium. Median SAFE caps have risen from about $15M in W21 to about $40M in P26, and Rebel's view is that the price is worth paying for the best companies.
Stage Focus
Rebel invests exclusively at seed stage, in YC companies at or around the batch. It has backed startups in every batch since Summer 2019 and a handful before that, and the portfolio now covers 325+ investments (the site lists 342 companies).
Check Size
No check size is published. Because the fund builds a 300+ company portfolio, individual checks are small relative to fund size. The check range in the structured profile is left empty rather than guessed.
Lead Tendency
Rebel writes small checks into YC SAFE rounds as part of a large diversified portfolio and does not present itself as a round lead. Lead tendency is recorded as unknown.
Recent Activity
The fund is active. Its site shows portfolio news from August to October 2026, including Vitalize's $31M Series A, Hop Aero's $11M raise, Jeeves's $110M stablecoin banking round, VideoGen's $3.3M seed, Multiplier's $6M seed, Metal's $4.5M raise, Axle's $17.5M round and Dili's $21.7M round led by Khosla Ventures. It hosted an LP excursion and annual general meeting in 2026.
Portfolio Highlights
Notable portfolio names include Airbyte (YC W20), Anara, Trigger.dev, Axle, Jeeves, Vitalize, Hop Aero, Albedo, Algen Biotechnologies and Asha Health. The portfolio spans fintech, healthcare, AI infrastructure and agents, biotech, space and hardware, and logistics.
Team
- Jared Heyman: Managing Partner, founder of CrowdMed (YC W13), author of the Rebel essays
- Luis Fortuño: Managing Director
- Justin Hilliard: Principal, Superwall (YC S21)
- Alexandra Espinal: Portfolio Development
- Investing partners: Steve Huffman (Reddit), Daniel Kan (Cruise), Max Mullen (Instacart), Trip Adler (Scribd), Sebastian Mejia (Rappi), Dan Siroker (Optimizely), Josh Reeves, Tomer London and Edward Kim (Gusto), and Jonathan Hirsch (Paradigm, non-YC biotech partner)
Decision Process
Investment decisions run through the partnership and the Rebel Theorem score, with founder interviews before investing. Founders in testimonials describe a fast, prepared and founder-friendly process.
Founder Preferences
Founders must be in Y Combinator. Rebel does not respond to unsolicited investment offers and tells founders to apply to YC instead. Founders praise the webinars, virtual sessions and portfolio programming Rebel runs after investing.
Geographic Focus
Geography follows YC, which is global. The fund is based in San Francisco, and the portfolio includes companies in Latin America, Vietnam and Europe.