Private company

Y Combinator

Y Combinator, LLC (YC) is an American technology startup accelerator and venture capital firm launched in March 2005 which has been used to launch more than 5,000 companies.1

Last updated Oct 18, 2026.

Overview

Mar 2005Founded1

Y Combinator, LLC (YC) is an American technology startup accelerator and venture capital firm launched in March 2005 which has been used to launch more than 5,000 companies. The accelerator program started in Boston and Mountain View, relocated to San Francisco in 2019, and was entirely online during the COVID-19 pandemic. Companies started via YC include Airbnb, Coinbase, Cruise, DoorDash, Dropbox, GOAT, Instacart, Reddit, Stripe, Scale AI, Deel, Helion Energy, Starcloud, Twitch, and Whatnot. Over 400 companies are worth more than $100M, and 100 are unicorns.2

How it started

History

Founded in 2005 by Paul Graham, Jessica Livingston, Robert Tappan Morris, and Trevor Blackwell, Y Combinator initiated operations with concurrent programs in Cambridge, Massachusetts, and Mountain View, California. However, operational complexities arising from managing two programs prompted a consolidation in January 2009, resulting in the closing of the Cambridge program and the centralization of activities in Silicon Valley.

In 2009, Y Combinator secured a $2 million investment led by Sequoia Capital, enabling increased annual funding for around 60 companies. Sequoia further supported YC in 2010 through an $8.25 million funding round, bolstering the organization's capability to accommodate a growing number of startups. Concurrently, Kirsty Nathoo joined the team, initially as an accountant, and subsequently as the Chief Financial Officer (CFO) in 2012. In 2011, Yuri Milner and SV Angel offered every Y Combinator company a $150,000 convertible note investment. The amount put into each company was changed to $80,000 when Start Fund was renewed.

Advisory roles were assumed by Harj Taggar and Alexis Ohanian in 2010, and Paul Buchheit and Taggar were named partners in November. Michael Seibel joined Y Combinator as a part-time partner in January 2013 before becoming a full-time partner in 2014. In September 2013, Y Combinator began funding nonprofit organizations that were accepted into the program after testing the concept with Watsi.

Sam Altman took part in Y Combinator's inaugural cohort in 2005 as a founder. In 2014, Paul Graham appointed him as president. Altman introduced a revised equity offering of $150,000 for a 7% stake. Under Altman, Peter Thiel joined as a visiting partner from 2015 to 2017.

Global outreach became evident in 2016 as YC partners embarked on visits to 11 countries (India, Israel, Nigeria, Denmark, Portugal, Sweden, Germany, Russia, Argentina, Chile and Mexico) to engage with founders and learn about international startup communities. That summer, Altman returned to the United States and worked on OpenAI. Leadership responsibilities were delegated to Ali Rowghani and Michael Seibel for YC Continuity and YC Core programs, respectively. Startup School, introduced in 2017, provided startups with online courses and personalized coaching. More than 1500 startups graduated from the program in its first year.

From Wikipedia’s article on Y Combinator, shared under CC BY-SA 4.0.2

Leadership

Who has led Y Combinator, and when. Pick a name to see everywhere that person has worked.

Timeline

  1. Mar 2005Founded Founded in Cambridge1

Sources

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