Michael Seibel Steps Down from Y Combinator After 12 Years

Michael Seibel steps down from the San Francisco-based Y Combinator (YC) as a group partner. After spending a decade at the accelerator, Seibel said he would move into a partner emeritus role. “The next adventure I’m excited to pursue is how I can help the government better serve its citizens,” he posted on X. 

Before joining YC, Seibel co-founded Justin.tv, which evolved into Twitch and was acquired by Amazon in 2014 for $970 million, and Socialcam, sold to Autodesk in 2012 for $60 million. 

During his time at YC, he served in various capacities, including as founder, group partner, managing director, and CEO of the accelerator. 

President and CEO Garry Tan shared a blog highlighting Seibel’s lasting impact on YC’s values, programs, and founder support.

Also, YC recently celebrated its 20th anniversary. Founded on March 11, 2005, by Paul Graham, Jessica Livingston, Trevor Blackwell, and Robert Tappan Morris, YC has played a pivotal role in nurturing early-stage startups, leading to the creation of over $800 billion in market value. Past YC alumni include Stripe, Airbnb, and Reddit.

YC held its Winter 2025 Demo Day on Wednesday, showcasing 160 new startups.

YC has shifted its focus from funding early-stage internet startups to AI startups. Group partner Jared Friedman spoke about the influence of AI within the startups as well. He said that one-quarter of the YC founders admitted that over 95% of their codebase was AI-generated. He pointed out that these were highly skilled founders who, just a year ago, would have built their products entirely on their own—but now, AI does the heavy lifting.