Reddit appointed to its board Michael Seibel, partner and CEO at the startup incubator Y Combinator, who fills the spot vacated by Reddit co-founder Alexis Ohanian. 

Last week, Ohanian stepped down from Reddit's board in support of the Black Lives Matter movement, and he called for a black leader to take his place. The resignation shined a light on Reddit's issues dealing with hate speech in certain corners of the platform. 

Seibel, who is African American, is a tech entrepreneur. He co-founded Justin.tv, which has since become Twitch, the popular streaming video site owned by Amazon. He also co-founded Socialcam. 

"I’ve watched Reddit become part of the core fabric of the internet," Seibel said in Reddit's announcement on Wednesday, "and I’m excited to help provide advice and guidance as Reddit continues to grow and tackle the challenges of bringing community and belonging to a broader audience.”  

Reddit is a site of 430 million monthly users who join "subreddits," which are community-run forums covering thousands of topics and interests. Some of the subreddits have become bastions of extremist and racist rhetoric, and Reddit has been criticized for not moderating the discussions. Moderation typically falls on the users who create the subreddits. 

Last week, some subreddits protested Reddit's loose hate speech enforcement policies. Moderators took subreddits private and disabled the ability to post as a show of solidarity with George Floyd.

Reddit CEO Steve Huffman promised to make changes. "As Reddit has grown, alongside much good, it is facing its own challenges around hate and racism," Huffman wrote on Friday. "We have to acknowledge and accept responsibility for the role we have played."