Given that NVidia can already license designs from ARM and given that companies will trust ARM less in rival NVidia's hands then in a neutral party it looks like the value of ARM is going to go way down after the sale, effectively lighting a giant pile of millions of dollars of economic value on fire. But the literature says that that's actually pretty typical of how mergers and acquisitions end up playing out. In general they're tributes to the CEO's ego that impoverish shareholders, though there are exceptions. I can't help but think that NVidia is paying $40B for a company that'll be worth $15B to them but would be worth $30B on the open market.