Edit - sorry, reply got lost, replying to @slick post 72486176...

Edit - sorry, reply got lost, replying to @slick post 72486176 above...

To be honest @slick, I don't know what the market knows or doesn't know, or what it has factored in and what it hasn't. If I did I'd no doubt be living the dream.

However, if the market does really know absolutely everything, and that information is always reflected in the share price, why do share prices ever actually change? And change in price sometimes multiple times per second, or change massively from just one day to the next?

By trying to profit from changes in share price, aren't you actually trying to take advantage of this inherent inefficiency and the fact that the market doesn't always know everything and what is known isn't always accurately reflected in the share price?

Put another way, let's say someone decided (for whatever reason - despondency, financial pressure, resentment, fat finger) to sell half a million shares of RAC into the current bid stack, sending the share price to $0, or close to it... what about the company (and its chances of future success or failure) has changed, other than the share price and register of shareholders?