Efficient Market Hypothesis Again Proven Wrong
Here is a practical example of how some investors are sometimes really irrational. Some morons have actually paid money for the stock of Delta airlines, even though it went bankrupt in September 2005 and even though it has long been clear that not even bondholders are going to get more than a fraction of their money. And bondholders are legally entitled to be paid back in full before stockholders can get a single penny.
And with some investors being this irrational, this implies that more rational investors have a chanse to make money the Efficient Market Hypothesis claims they cannot make.