Utilize your financial knowledge, give your answer or opinion to the input question or subject . Answer format is not limited.

Efficient markets hypothesis and performance of IPO shares after lock-up period
There are rules that prevent two of the reactive measures you suggest from occurring. First, on the date of and shortly following an IPO, there is no stock available to borrow for shorting. Second, there are no put options available for purchase. At least, none that are listed, of the sort you probably have in mind. In fact, within a day or two of the LinkedIn IPO, most (all?) of the active equity traders I know were bemoaning the fact that they couldn't yet do exactly what you described i.e. buying puts, or finding shares to sell short. There was a great deal of conviction that LinkedIn shares were overpriced, but scant means available to translate that market assessment into an influence of market value. This does not mean that the Efficient Markets Hypothesis is deficient. Equilibrium is reached quickly enough, once the market is able to clear as usual.