Jensen Huang's Exit Puts CUDA Architect Ian Buck at Nvidia's Center

Nvidia named CFO Colette Kress interim CEO on Tuesday after Jensen Huang resigned following nearly a week of revelations about extramarital relationships with multiple women, including one speculated to be an agent of the Chinese government. One of the executives whose influence grows the moment Huang walks out the door is Ian Buck, Nvidia's 48-year-old vice president of hyperscale and high-performance computing.

Buck has worked alongside Huang since 2004, when he began building Compute Unified Device Architecture. CUDA started with two people and two libraries. Today it supports more than 900 libraries and AI models, with each library corresponding to an industry using Nvidia technology. CUDA is the platform from which Nvidia jumped to, at one point, 90% market share in AI computing. It's how the company defends its moat.

Buck's heft has led industry analysts to repeatedly cite him as a possible successor to Huang — long before one was needed.

What did it take to build CUDA?

Buck focused on graphics since his undergrad days at Princeton in the late 1990s. "Computer graphics was such a dweebie field," said Stephen Witt, author of "The Thinking Machine," which details Nvidia's rise to the world's most valuable company. "There was a stigma to working in computer graphics — you were maybe some kind of man-child if this was your focus."

While pursuing his Ph.D. at Stanford, Buck connected multiple GPUs to push them to their limits. He and his cohort used the chips to play "Quake" and "Doom" before he became fixated on proving GPUs could do anything. He received funding from Nvidia and the Defense Advanced Research Projects Agency to develop Brook, a programming language applying GPU power beyond graphics. Nvidia hired him when it saw the work.

He wasn't alone. John Nickolls, then director of architecture for GPU computing, was instrumental in building CUDA until his death from cancer in 2011. "Both Nickolls and Buck had this obsession with making computers go faster in the way that a Formula 1 mechanic would have an obsession with making the race car go faster," Witt told Business Insider.

The team built a framework letting developers use the C language to harness the GPU's ability to run immense calculations simultaneously — parallel computing for the masses. The payoff wasn't inevitable. Huang insisted every chip be compatible with the software even though hardly anyone used the free tool, and Nvidia lost millions of dollars for more than a decade because of CUDA. When ChatGPT launched, Nvidia was already powering the AI computing revolution now drawing trillions in infrastructure spending.

Who is Ian Buck?

Business Insider spoke with four people who worked with Buck at Stanford, Nvidia, or both. They describe him as gregarious and easygoing but capable of intensity when goals are on the line, and focused on results rather than theory.

Dion Harris, Nvidia's senior director of high-performance computing and AI factory solutions, says Buck volleys from rapid technical lines of thought to plain layman's terms — describing proteins as "complicated 3D squigglies in your body." Paul Bloch, president of Nvidia partner DDN, notes Nvidia's leaders don't choose between showmanship and code: "A lot of developers are amazing, but they say, 'Leave me alone. I'm going to write my code in the mountains somewhere."

Can anyone break CUDA's dominance?

Competition is coming faster than ever. On the first night of GTC 2025, competitors convened by TensorWave — an AI cloud company using only AMD chips — held an event entitled "Beyond CUDA." TensorWave cofounder Jeff Tatarchuck said it included more than "24 presenters talking about what they're doing to overcome the CUDA moat." AMD is making an explicit effort to catch up on the software side, but analysts say it's not there yet. More jobs requiring CUDA skills were posted in 2026 than in 2025, according to labor analytics platform Lightcast.

Buck keeps close tabs on researchers. "One of the most challenging parts of my job often is to try to predict the future, but AI is always surprising us," he said at a Bank of America conference in 2025. He called DeepSeek's team "one of the best CUDA developers out there."

Who's Nvidia's next CEO?

"Jensen has three right-hand men," Intel CEO Lip-Bu Tan told BI, naming Buck, VP of GPU Engineering Jonah Alben, and CFO Colette Kress. Morningstar analyst Brian Colello said Thursday that prediction markets have identified former Nvidia VP Rene Haas, current CEO of Arm, as a potential external replacement, alongside internal candidates Kress and Buck. Witt's take: "I don't think Ian spends a lot of time doing business strategy. He's more like the world's best mechanic."

Nvidia declined to make Buck available for an interview and declined to comment. With analysts warning that Nvidians may be likelier to leave after Huang's exit, Buck's dual role as technical magnet and potential CEO candidate makes him central to whether Nvidia keeps its lead.