Premises on which the Efficient Market Hypothesis is built upon The Efficient Market Hypothesis tells us that stocks are "fairly priced" (i.e. not systematically over- or under-valued). That is, stock prices reflect all information that is already known about them. This is because any information from current or past events are already "absorbed" by the market. What is this "asborption" of information by the market supposed to mean? The market is comprised of its participants, buyers and sellers. I would also like to ask if the Efficient Market Hypothesis is built upon the following premises:


All market participants have perfect information at all times, i.e. they know the operations of the companies listed on the stock exchange fully well and that they are also well-equipped with the financial knowledge required to interpret any economic news that may affect the performance of the listed companies.
All market participants respond rationally and make decisions using the marginalist principle. 
Market participants are able to assess the circumstances readily at any one time and are able to respond to any new economic information (e.g. government macroeconomic policy changes, changes to corporate earnings etc.) instantly. 


I just learnt about this concept and so I would just wish to seek clarification on it.
The efficient market hypothesis does not require everyone being omniscient. It works through the supply/demand and price mechanism. 

For example, imagine that you have private information that a company X is doing bad (without being a manager or other person banned from insider trading). If company X is doing bad then sooner or later it’s stock price will have to go down, so if you own it’s stock you would sell it now while the price is still high or if you don’t own the stock you would short sell it.

However, as you start selling the stock you are pushing the price down. Since it’s profitable for you to sell or short sell as long as the market price is above the actual value of the company, you would do that so much that the price would eventually be driven to the point where the price is exactly equal it’s value.

The central assumption of the efficient market hypothesis is the perfect market assumption. In a perfect market there are no transactions costs, information is costless, investors are rational. In the real world however, these assumptions do not completely hold and the market is not fully efficient. 

This being said, there is evidence that despite these imperfections markets are efficient to a certain extent as prices do adjust in response to new information. In fact it’s astonishingly hard to beat the market, and difficult to find deviations from the efficient market hypothesis empirically but now we know they exist.