are you too young to have lived through the multiple recessions that have happened in the past few decades or Bernie Madoff or Enron? Or Theranos and FTX? and that's just off the top, give me ten minutes to dig in and I'll get you at least twenty more
None of those were the result of mergers.
Pedantic. The point was "aren't investors rational" and they clearly hop on short term fads to their and our detriment. Plus saying Enron wasn't a product of a merger is very funny