The New Y Combinator (jaredheyman.medium.com)

Y Combinator has visibly shifted since Garry Tan became CEO amid the AI boom: Rebel Fund’s large YC dataset and their Rebel Theorem 4.0 ML model show founders are younger (average down from ~29 to ~26 and falling, with more founders under 25 than over), more technical, more likely to come from top-20 universities and elite employers (now nearly half vs ~25% a decade ago), and increasingly based in the San Francisco Bay Area (approaching 85%). Rebel also detects personality shifts (lower Dominance, higher Conscientiousness), a spike in YC-alumni founders, and a stronger emphasis on community and Silicon Valley pedigree. For investors and researchers this matters because Rebel’s model identifies founder-age and related experience metrics as powerful predictors of outcome, with a “sweet spot” at 26–30 years for the highest odds of a “success” (defined by Rebel as $60M+ valuation and still operating). Founders <26 are likelier to produce “dead” startups and >30 to produce “zombie” ones, but younger cohorts score better on 4 of 6 founder–product fit metrics. The Bay-centric shift raises variance—SF startups tend to both win big and fail more often. Bottom line: YC is “more YC” — different, not simply better or worse — and the reshaped founder mix changes risk profiles and signal interpretation for early-stage AI/ML investors.