Brian O'Kelley, New York, New York, United States — Brian O’Kelley is an angel investor and serial. See portfolio, sector focus and contact routes.
Brian O’Kelley is an angel investor and serial entrepreneur based in Brooklyn, New York, who previously served as co-founder and CEO of AppNexus, an ad tech firm acquired by AT&T for $1.6 billion in 2018. He currently leads Scope3, a sustainability startup decarbonizing digital advertising, and holds advisory roles at firms like Blacksheep Ventures and Armis. His investment thesis targets early-stage technology companies, with a focus on advertising, enterprise software, artificial intelligence, B2B SaaS, and supply chain technology. O’Kelley typically invests from seed to Series B, with check sizes ranging from $250,000 to $4 million based on recorded rounds. Notable portfolio companies include Armis, ICX Media, Siftery, and Firsthand, alongside earlier investments in Invite Media and MediaMath. He is widely recognized as the inventor of programmatic advertising and the online ad exchange, a distinction that shapes his distinctive point of view on ad tech infrastructure.
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