说几句:market efficiency. that means you cannot earn abnormal returns and follow random walk. for individual equities, play the beta, and you can make some unexplainable January effect. short at May is also the other unexplainable abnormal return.
假如美国没了market efficiency, 就完了。 这就是补男克拼命要救的原因。现在流动性好了,但不代表不能空!