In 2018, a software glitch at Y Combinator accepted all 15,000 startups that had applied to a new batch of startup schools. A few hours later the same applicants learned they had been rejected. The outcry that followed ended with YC accepting every one of them.
It is an odd footnote for an outfit that has been used to launch more than 5,000 companies. Founded in March 2005 by Paul Graham, Jessica Livingston, Robert Tappan Morris and Trevor Blackwell, YC counts Airbnb, Coinbase, Cruise, DoorDash, Dropbox, GOAT, Instacart, Reddit, Stripe, Scale AI, Deel, Helion Energy, Starcloud, Twitch and Whatnot among its alumni. Over 400 of its companies are worth more than $100 million, and 100 are unicorns. YC also runs Hacker News.
Two cities, then one
The first programs ran side by side in Cambridge, Massachusetts, and Mountain View, California. Running two was a headache, so in January 2009 YC closed the Cambridge program and moved everything to Silicon Valley.
Money followed. Sequoia Capital led a $2 million investment in 2009 and an $8.25 million round in 2010. In 2011, Yuri Milner and SV Angel offered every YC company a $150,000 convertible note. The figure dropped to $80,000 when the Start Fund was renewed.
Altman, OpenAI and the AI link
Sam Altman was in YC’s first cohort in 2005 as a founder. Graham named him president in 2014, and Altman introduced a revised offer of $150,000 for a 7% stake. In October 2015 YC set up YC Research for long-term fundamental work, with $10 million from Altman. OpenAI was its first project.
In 2016, YC partners visited 11 countries to meet founders. That summer Altman returned to the United States and worked on OpenAI.
Startup School arrived in 2017, offering online courses and personalized coaching, and more than 1,500 startups graduated in its first year. Geoff Ralston replaced Altman as president in 2019. The summer 2020 batch ran remotely because of COVID-19.
In January 2022 YC settled on a standard deal of $500,000: $125,000 for 7% equity, plus $375,000 on an uncapped safe with a most-favored-nation clause. That summer it cut its intake by 40 percent, from 414 companies to 250. Garry Tan took over as president and CEO in January 2023.
Where it stands
In June 2025 YC held its first AI Startup School in San Francisco for 2,500 top computer science undergraduates, master’s students and PhD candidates in AI. Elon Musk, Sam Altman, Satya Nadella, Andrej Karpathy, Andrew Ng and Fei-Fei Li were among the speakers.
On March 30, 2026, YC announced its fastest unicorn yet. Starcloud raised a $170 million Series A at a $1.1 billion valuation, led by Benchmark and EQT Ventures, 17 months after demo day. As of 2026, YC has invested in over 5,668 companies with a combined valuation of $600 billion.
