Y Combinator, the prestigious seed accelerator that has spawned an impressive list of big-name tech companies (Dropbox, Reddit, Airbnb and Weebly, to name just a few) is getting a new president.

Paul Graham, who co-founded the accelerator, announced in a blog post that he is passing the reins to Sam Altman, a current Y Combinator partner.

In the post, Graham directly addressed his decision to step down. "YC needs to grow, and I'm not the best person to grow it," he wrote. "Sam is what YC needs at this stage in its evolution."

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Altman was one of the founders in the first batch of startups the accelerator funded back in 2005. (He co-founded the location-based social networking mobile application Loopt). In his post, Graham claimed he has been trying to recruit Altman for the job since 2012.

"He's one of those rare people who manage to be both fearsomely effective and yet fundamentally benevolent -- which, though few realize it, is an essential quality in early stage investing," he wrote. "Sam is one of the smartest people I know, and understands startups better than perhaps anyone I know, including myself.  He's the one I go to when I want a second opinion about a hard problem."

Graham said he will continue to work with the accelerator as an advisor, and expects Y Combinator to continue to grow: "There will be a lot more startups in 10 years than there are now, and if YC is going to fund them, we'll have to grow proportionally bigger."

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