That's not how it works. The investment is an asset on the balance sheet, it is very unlikely to reduce taxable profits. I don't know the US corporation tax situation much, but if it's anything like the UK then you couldn't use that to offset profits for the year. You could if the investment failed, but then you've lost a lot more money than the tax saving (as you've lost the entire $4bn investment).
You might be right that Anthropic could then spend that money back with AWS, but that would again be subject to tax on any profits it generates for AWS. Also, if they spent (say) $2bn of the money with AWS but had nothing to show for it, when Anthropic raises again you'd expect the valuation to decrease substantially.
I very much doubt it is a tax saving mechanism, nor do I think it is a particularly good way to juice sales (compared to spending say $4bn on marketing, or discounts, or whatever).
You might be right that Anthropic could then spend that money back with AWS, but that would again be subject to tax on any profits it generates for AWS. Also, if they spent (say) $2bn of the money with AWS but had nothing to show for it, when Anthropic raises again you'd expect the valuation to decrease substantially.
I very much doubt it is a tax saving mechanism, nor do I think it is a particularly good way to juice sales (compared to spending say $4bn on marketing, or discounts, or whatever).