the efficient market

The company was founded in 1980 and currently has a market cap of approx. 4 billion US$.
But at the end of last year famous investor Bill Ackman made a presentation suggesting that Herbalife is indeed a worthless Ponzi scheme and he disclosed a significant billion dollar short position. Subsequently the stock dropped from mid-fourties to the mid-twenties. But when equally well-known investor Dan Loeb disclosed that he is long on Herbalife the stock recovered - until it dropped again (*).
At this point Carl Icahn stepped into the ring and disclosed a 13% stake in the company. He is no friend of Bill Ackman and it seems that he would like to organize a 'short squeeze' to get his enemy in trouble. Subsequently the stock jumped above fourty dollars before it settled in the high thirties yesterday.

Meanwhile I have three questions for Prof. Fama and French: How long will the efficient market need to figure out if Herbalife is a worthless Ponzi scheme or a growth company with an undervalued stock?
Are Bill Ackman, Dan Loeb and Carl Icahn behaving as rational agents?
If HLF is indeed a worthless stock, will it drop to zero immediately, or will we see Mr. Icahn's 'short squeeze' first?

I also have a question for those who believe in the regulation of financial markets: How long will the FTC need to figure this out and will they have the courage to shut down a multi-billion dollar company, siding with Mr. Ackman?


(*) I have no position in this stock and have no intention to initiate one. I read (only) part of Mr. Ackman's presention and found it quite convincing - but I am neither an accountant nor a lawyer.