Utilize your financial knowledge, give your answer or opinion to the input question or subject . Answer format is not limited.

Equation to determine if a stock is oversold and by how much?
There are those who would suggest that due to the Efficient Market Hypothesis, stocks are always fairly valued. Consider, if non-professional posters on SE (here) had a method that worked beyond random chance, everyone seeking such a method would soon know it. If everyone used that method, it would lose its advantage. In theory, this is how stocks' values remain rational.  That said, Williams %R is one such indicator. It can be seen in action on Yahoo finance -  In the end, I find such indicators far less useful than the news itself. BP oil spill - Did anyone believe that such a huge oil company wouldn't recover from that disaster? It recovered by nearly doubling from its bottom after that news. A chart of NFLX (Netflix) offers a similar news disaster, and recovery.  Both of these examples are not quantifiable, in my opinion, just gut reactions. A quick look at the company and answer to one question - Do I feel this company will recover? To be candid - in the 08/09 crash, I felt that way about Ford and GM. Ford returned 10X from the bottom, GM went through bankruptcy. That observation suggests another question, i.e. where is the line drawn between 'investing' and 'gambling'? My answer is that buying one stock hoping for its recovery is gambling. Being able to do this for 5-10 stocks, or one every few months, is investing.