FT uses "underwater" because the deal was $300 Billion and the stock has lost $315 Billion in market cap since the deal. That's a bit of a stretch, but the rest of the article is very good.
And as it won't be obvious to everyone here: Alphaville is one of the few free parts of FT online. You need to create an account to access it, but don't need a paid subscription.
Yea these market cap discussions are always a bit meaningless actually, stocks can be volatile for many reasons… its not like they actually lost the delta
