Microsoft chose not to exercise a nearly $12 billion option to buy more data-center capacity from CoreWeave, people familiar with the matter said, a sign that big tech companies are starting to right-size and tailor their AI budgets.CoreWeave, which is readying for the year’s most closely watched IPO, quickly found another buyer — OpenAI snapped up the contract last week — and Microsoft has reiterated its plan to spend $80 billion on AI. Nvidia CEO Jensen Huang told thousands of eager fans at th...