Michael Seibel

In 2005, Seibel graduated from Yale UniversityYale UniversityYale University is a research university in New Haven, Connecticut. Its predecessor, the Collegiate School, received a charter in 1701. Trustees chose New Haven in 1716; the institution became Yale College in 1718 and Yale University in 1887. Yale provides undergraduate, graduate and professional education and has 14 undergraduate residential colleges. As of October 2026, its president was Maurie McInnis, who took office in July 2024. In 2026, Yale expanded aid for incoming undergraduates and celebrated its 325th anniversary.Open the full entry with a BA in political science. In 2006, he served as finance director for Kweisi Mfume’s U.S. Senate campaign in Maryland.⁠[1][2][3]

In October 2006, Seibel co-founded the live streaming website Justin.tv with Justin KanJustin KanJustin Kan is an American internet entrepreneur and investor who rose to prominence in 2007 with Justin.tv, which broadcast his life around the clock from a head-mounted camera. He went on to co-found the game streaming platform Twitch, which Amazon acquired for about $970 million in 2014; he also founded the legal technology company Atrium and co-founded the gaming payments platform Stash.Open the full entry, Emmett Shear, and Kyle Vogt; the company was part of Y Combinator’s Winter 2007 batch. From June 2007 to October 2011, he served as CEO of Justin.tv.⁠[3][4][5]

In 2011, the gaming streaming business Twitch was spun off into a service of its own; in February 2014, the company was renamed Twitch Interactive, and that same year it was sold to Amazon for $970 million.⁠[6][1]

Seibel was an early advisor to Airbnb and helped bring the company into Y Combinator.⁠[7]

Seibel subsequently co-founded the mobile video app Socialcam and served as its CEO. On July 17, 2012, Autodesk announced that it had signed a definitive agreement to acquire Socialcam for $60 million.⁠[5][8][1]

In January 2013, Seibel joined Y Combinator as a part-time partner, becoming a full-time partner in October 2014.⁠[9][10]

On September 13, 2016, Y Combinator announced that Seibel would become CEO of YC Core, the startup accelerator business, which would thereafter be called simply YC.⁠[4]

On June 5, 2020, Reddit co-founder Alexis Ohanian announced that he was stepping down from Reddit’s board of directors and asked that his seat be filled by a Black candidate. On June 10, Reddit announced the appointment of Seibel as a director. As of 2026, he remains a Reddit director and has been nominated for re-election to serve until the 2027 annual meeting.⁠[11][11][5]

In December 2020, Dropbox announced that Seibel was joining its board of directors.⁠[2]

On March 15, 2024, Seibel announced that after 8 years as head of the YC accelerator he was handing over his leadership responsibilities, returning to his original role of Group Partner effective at the end of the Winter 2024 batch.⁠[12]

In March 2025, after more than 12 years at Y Combinator, Seibel transitioned to the role of Partner Emeritus and said he hoped to help government better serve its citizens. He also serves on the board of Kalshi.⁠[13][14][3]

Personal website: https://www.michaelseibel.com/ (opens in a new window).⁠[14]

X: Public account: https://x.com/mwseibel (opens in a new window).⁠[14]

LinkedInLinkedInLinkedIn is a social networking platform for professionals. It was founded in 2002 by Reid Hoffman and others, launched in 2003, and listed on the New York Stock Exchange in 2011; after Microsoft acquired it for approximately $26.2 billion in 2016, it became a wholly owned Microsoft subsidiary. Its revenue comes from membership subscriptions, advertising, and recruitment solutions.Open the full entry: Public profile: https://www.linkedin.com/in/mwseibel/ (opens in a new window).⁠[9]