I'm not disagreeing with your point that AIG was speculating or not. There simply isn't enough information surrounding their position(s) to formulate a clear answer. It is true that institutions, even very large ones, will dabble in speculative stocks from time to time. To that end, I would expect them to have a shorter leash with unproven, pre-revenue companies that are heavily involved with litigation.
My point is the Vringo story has undergone several significant changes along the way and any competent institution will adjust their investment thesis with the changing story. That doesn't mean their research or DD was wrong, it just means that at some point the investment/speculative trade no longer meshed with the institution's strategy -- short or long term.
In that regard, they are exactly opposite many retail investors who buy a stock and become emotionally attached to it. Or buy a stock and have rose-colored glasses on. Or buy a stock and won't sell until they can break-even in the future... or, etc. etc. etc.
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