For the following two statements, decide whether the described phenomenon is a violation of the semi-strong form of the efficient market hypothesis, and why.

Suppose you are long-horizon stock investor: you plan to hold stocks for long periods of time. You know that the stock market experiences booms and busts. Booms are often caused by other investors being overly optimistic, and busts are often caused by other investors being overly pessimistic and selling in panics. Is it more profitable for you to buy stocks in booms or busts? Why?