The fact that each investor may value a stock differently, doesn't make it. inefficient. It means that the stock has a different value to each investor, that is no different then how a person may value a piece of property or food for example. One person may think the price of an organic peach is correct, while another (like myself) thinks the product is OVER priced. A product, service, stock etc. has a different value to virtually any person. Does that mean ANY market can be efficient?

what do you mean "efficient"?

As far as the market is concerned the term is meaningless

The market is solely based on supply and demand

The more shares there are available than buyers who want to buy them then the price falls

fewer shares than buyers then the price rises

Apart from the time lag for the price to adjust, the market is 100% efficient

How people assess the "value" of a share is irrelevent to the operation of the market. Its ONLY relevent to the price THEY are willing to pay for a share (or sell it).

The market will automatically adjust when they make the decision to buy/sell

I think the stock market is rigged

I find the debate very interesting about the US Stock market being efficient or not. For instance, one article read not "all investors perceive all available information in precisely the same manner."

The article also explained further that "if one investor looks for undervalued market opportunities while another investor evaluates a stock on the basis of its growth potential, these two investors will already have arrived at a different assessment of the stock’s fair market value. Therefore, one argument against the EMH points out that, since investors value stocks differently, it is impossible to ascertain what a stock should be worth under an efficient market."