The efficient-market hypothesis (EMH) is a hypothesis in financial economics that states that asset prices reflect all available information.
This is essentially what everyone refers to when they yell out “priced in”, but they do realize that it's a hypothesis correct? It's just a way for us to specify that all the variables in the stock market can cause the others to change. However, it has it's own flaws. The 2008 crisis for example and I would argue most financial crises put stress on the hypothesis because it should have already been priced in and thus could have been averted.
It also doesn't make sense if every new piece of information is priced in immediately, there shouldn't be spiky volatile activity on stocks with little to no news but we see that time and time again. Does anyone have any actual evidence that the EMH has useful value?
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