Why? There’s $80B of dilution from new shares issued, so to keep share prices constant market cap would have to increase by $80B. Simultaneously, there $80B in additional assets on the balance sheet, so if the company was previously correctly valued at $N market cap it would now be correctly valued at $N+$80B market cap, right? My intuition is that capital raises, just like stock buybacks, should be first-order (“mechanically”) share price neutral.

They added $80 out of a $4.5T market cap, which means redistributing ~1.67% of value from shares outstanding to the new shares.

So being down 1.7% is literally exactly what you'd expect.

Sure but people are no longer expecting these kinds of actions to generate equity gains. Before it was expected the growth would outpace the cost of capital, leading to equity appreciation. The directional change is what is interesting.