> In order to sell high after wrecking the long term future of a company, you've got to fool a lot of sophisticated investors. This seems implausible to me.

When you put it that way, it does sound implausible. But it demonstrably happens, so lets consider how that explanation may be wrong.

You don't necessarily have to fool a lot of sophisticated investors, you have to fool people/firms with sufficient funds available to invest, who can be talked into the belief that they are taking advantage of opportunity the rest of the market is missing, perhaps one which is uniquely available to them because of synergies.

Often this can be one person or firm rather than a lot of investors (sophisticated or not) -- its not as if acquisitions where the acquirer pays above market price and ends up a few years later taking a huge charge when its expectations fail to pan out are unheard of.

And this makes sense. If firms can make foolish decisions in running their business which negatively impact the future of the company, one form this can take is buying some other business at an unjustified price where someone else had already made a foolish decisions that negatively impacted the future value of that business.

I'm sure it happens here and there. But generally? No. The people who make the bulk of the trades (i.e. move the markets) have every incentive to not buy at a high price a company that has eaten their seed corn. They employ analysts whose sole job is to investigate those companies.

If you know of specific companies that have destroyed their future for a short term stock gain, you stand to make a fortune by short selling the stock.