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. "To my knowledge, there's no universal equation, so this could vary by individual/company.   The equation I use (outside of sentiment measurement) is the below - which carries its own risks: This equations assumes two key points: Anything over 1.2 is considered oversold if those two conditions apply.  The reason for the bear market is that that's the time stocks generally go on ""sale"" and if a company has a solid balance sheet, even in a downturn, while their profit may decrease some, a value over 1.2 could indicate the company is oversold. An example of this is Warren Buffett's investment in Wells Fargo in 2009 (around March) when WFC hit approximately 7-9 a share.  Although the banking world was experiencing a crisis, Buffett saw that WFC still had a solid balance sheet, even with a decrease in profit.  The missing logic with many investors was a decrease in profits - if you look at the per capita income figures, Americans lost some income, but not near enough to justify the stock falling 50%+ from its high when evaluating its business and balance sheet.  The market quickly caught this too - within two months, WFC was almost at $30 a share. As an interesting side note on this, WFC now pays $1.20 dividend a year.  A person who bought it at $7 a share is receiving a yield of 17%+ on their $7 a share investment. Still, this equation is not without its risks.  A company may have a solid balance sheet, but end up borrowing more money while losing a ton of profit, which the investor finds out about ad-hoc (seen this happen several times).  Suddenly, what ""appeared"" to be a good sale, turns into a person buying a penny with a dollar.  This is why, to my knowledge, no universal equation applies, as if one did exist, every hedge fund, mutual fund, etc would be using it. One final note: with robotraders becoming more common, I'm not sure we'll see this type of opportunity again.  2009 offered some great deals, but a robotrader could easily be built with the above equation (or a similar one), meaning that as soon as we had that type of environment, all stocks fitting that scenario would be bought, pushing up their PEs.  Some companies might be willing to take an ""all risk"" if they assess that this equation works for more than n% of companies (especially if that n% returns an m% that outweighs the loss).  The only advantage that a small investor might have is that these large companies with robotraders are over-leveraged in bad investments and with a decline, they can't make the good investments until its too late.  Remember, the equation ultimately assumes a person/company has free cash to use it (this was also a problem for many large investment firms in 2009 - they were over-leveraged in bad debt)." "What you are seeking is termed ""Alpha"", the mispricing in the market. Specifically, Alpha is the price error when compared to the market return and beta of the stock. Modern portfolio theory suggests that a portfolio with good Alpha will maximize profits for a given risk tolerance. The efficient market hypotheses suggests that Alpha is always zero. The EMH also suggests that taxes, human effort and information propagation delays don't exist (i.e. it is wrong). For someone who is right, the best specific answer to your question is presented Ben Graham's book ""The Intelligent Investor"" (starting on page 280). And even still, that book is better summarized by Warren Buffet (see Berkshire Hathaway Letters to Shareholders). In a great disservice to the geniuses above it can be summarized much further: closely follow the company to estimate its true earnings potential... and ignore the prices the market is quoting. ADDENDUM: And when you have earnings potential, calculate value with: NPV = sum(each income piece/(1+cost of capital)^time) Update: See http://finance.fortune.cnn.com/2014/02/24/warren-buffett-berkshire-letter/ ""When Charlie Munger and I buy stocks..."" for these same ideas right from the horse's mouth"
That's a rearrangement of the fisher equation; which is the correct way to determine real rates.  However, people often use the approximation real ≈ nominal - inflation; and if you're doing this for homework on software that is looking for exactly 1 numerical answer, they may be expecting you to use that instead.  Real interest rate is less formal nomenclature and refers to using the approximation.  Inflation-adjusted return is the fisher equation.   In the real world you will use the approximation when you're figuring out a real rate while you're talking mid-sentence during a meeting; and use the fisher equation in spreadsheets/calculations. It could be an endless number of reasons for it.  It could simply just be a break through a long term resistance causing technical traders to jump in.  It could be an analyst putting out a buy recommendation.  If fundamentals have not changed then maybe the technicals have changed. Momentum could have reached an oversold position causing new buyers to enter the market. Without knowing the actual stock, its fundamentals and its technicals, no one will ever know exactly why. "Of course it can. This is a time value of money calculation. If I knew the maturity date, or current yield to maturity I'd be able to calculate the other number and advise how much rates need to rise to cause the value to drop from 18 to 17. For a 10 year bond, a rise today of .1% will cause the bond to drop about 1% in value. This is a back of napkin calculation, finance calculators offer precision. edit - when I calculate present value with 34 years to go, and 5.832% yield to maturity, I get $14.55. At 5.932, the value drops to $14.09, a drop of 3.1%.  Edit - Geo asked me to show calculations. Here it goes - A) The simplest way to calculate present value for a zero coupon bond is to take the rate 5.832%, convert it to 1.05832 and divide into the face value, $100. I offer this as the ""four function calculator"" approach, so one enters $100 divided by 1.05832 and repeat for the number of years left. A bit of precision is lost if there's a fractional year involved, but it's close. The bid/ask will be wider than this error introduced.  B) Next - If you've never read my open declaration of love for my Texas Instruments BA-35 calculator, here it is, again. One enters N=34 (for the years) FV = 100, Rate = 5.832, and then CPT PV. It will give the result, $14.56.  C) Here is how to do it in Excel -  The numbers in lines 1-3 are self evident, the equation in cell B4 is =-PV(B3/100,B1,0,B2) - please note there are tiny differences in the way to calculate in excel vs a calculator. Excel wants the rate to be .05832, so I divided by 100 in the equation cell.  That's the best 3 ways I know to calculate present value. Geo, if you've not noticed, the time value of money is near and dear to me. It comes into play for bonds, mortgages, and many aspect of investing. The equations get more complex if there are payments each year, but both the BA-35 and excel are up to it." Hopefully, before you invested in this stock, you evaluated the company.  You looked at the financial information about the company and where the company was headed, and evaluated whether the stock was undervalued or overvalued.  Hopefully, you determined that the stock was undervalued at the time you bought it. The thing to do now is to reevaluate the stock.  Do you think the stock is overvalued or undervalued right now?  If you didn't own it, would you buy it today?  Instead of looking at the past performance of the stock, you want to try to determine which direction the stock will go from today.  If you wouldn't buy it today at it's current price, then you should sell. If you have no idea how to do this evaluation, neither do I.  For me, with the investing knowledge I have right now, investing in an individual stock would be way too risky.  If you don't know how to evaluate a stock and determine if it is a good buy or not, then you should stay away from individual stocks and instead invest in stock mutual funds, which lower the risk by diversifying over lots of stocks. Generally speaking.  1. Take the position size / average daily volume.  2. Multiply that number by 10 or whatever 1/whatever % of volume you think you can execute, ( you can at best acct for 10 percent of traded volume on a day).  3. You now have days until liquidation (x)  4. Take the days until liquidation sample the return over  time x. I.e. if days until liquidation is 10, you would sample 10 day returns.  5. Calculate the distribution characteristics of this window (mean, var, skew, kurt) and calculate VaR based on some confidence.  You can now have a liquidity risk expected loss and a VaR.  If position is on margin don't forget to add the interest cost.  Note: Instead of taking 10 day return, you can take the 10 day VWAP and calculate return between Open and 10 day vwap. you need to use easy programming language to imply onto a scan  where you enter Scan all stocks  display if volume < (less than) 100 P/E can use various estimates in its calculation as one could speculate about future P/E rations and thus could determine a future valuation if one is prepared to say that the P/E should be X for a company. Course it is worth noting that if a company isn't generating positive earnings this can be a less than useful tool, e.g. Amazon in the 1990s lost money every quarter and thus would have had a N/A for a P/E. PEG would use P/E and earnings growth as a way to see if a stock is overvalued based on projected growth. If a company has a high P/E but has a high earnings growth rate then that may prove to be worth it. By using the growth rate, one can get a better idea of the context to that figure. Another way to gain context on P/E would be to look at industry averages that would often be found on Yahoo! Finance and other sites. I've had luck finding old stock information in the Google scanned newspaper archives. Unfortunately there does not appear to be a way to search exactly by date, but a little browsing /experimenting should get what you want. For instance, here's a source which shows the price to be 36 3/4 (as far as I can read anyway) on that date.