Nvidia just approved the biggest buyback increase ever — $150 billion on top of its existing program, for a total of $235 billion. But a buyback authorization is permission, not spending. To use it all by fiscal 2028, Nvidia would have to roughly double its record repurchase pace. Here's the math, the 3 scenarios, and the numbers that will decide whether this is a real capital-return machine or just a very large permission slip.