How to calculate the closing price percentage change for a stock?
The previous day's close on Thursday 10th October was 5,000.00 The close on Friday 11th October is 5,025.92 So the gain on Friday was 25.92 (5025.92 - 5000) or 0.52% (25.92/5000 x 100%). No mystery!
"Edited: Pub 550 says 30 days before or after so the example is ok - but still a gain by average share basis.  On sale your basis is likely defaulted to ""average price"" (in the example 9.67 so there was a gain selling at 10), but can be named shares at your election to your brokerage,  and supported by record keeping. A Pub 550 wash might be buy 2000 @ 10 with basis 20000, sell 1000 @9 (nominally a loss of 1000 for now and remaining basis 10000), buy 1000 @ 8 within 30 days.   Because of the wash sale rule the basis is 10000+8000 paid + 1000 disallowed loss from wash sale with a final position of 2000 shares at 19000 basis.  I think I have the link at the example:  http://www.irs.gov/publications/p550/ch04.html#en_US_2014_publink100010601" Try to find the P/E ratio of the Company and then Multiply it with last E.P.S, this calculation gives the Fundamental Value of the share, anything higher than this Value is not acceptable and Vice versa. "The question mentions a trailing stop. A trailing stop is a type of stop loss order. It allows you to protect your profit on the stock, while ""keeping you in the stock"". A trailing stop is specified as a percentage of market price e.g. you might want to set a trailing stop at 5%, or 10% below the market price. A trailing stop goes up along with the market price, but if the market price drops it doesn't move down too. The idea is that it is there to ""catch"" your profit, if the market suddenly moves quickly against you. There is a nice explanation of how that works in the section titled Trailing Stops here. (The URL for the page, ""Tailing Stops"" is misleading, and a typo, I suspect.)" "Their algorithm may be different (and proprietary), but how I would to it is to assume that daily changes in the stock are distributed normally (meaning the probability distribution is a ""bell curve"" - the green area in your chart).  I would then calculate the average and standard deviation (volatility) of historical returns to determine the center and width of the bell curve (calibrating it to expected returns and implied volaility based on option prices), then use standard formulas for lognormal distributions to calculate the probability of the price exceeding the strike price. So there are many assumptions involved, and in the end it's just a probability, so there's no way to know if it's right or wrong - either the stock will cross the strike or it won't." What you're referring to is the yield.  The issue with these sorts of calculations is that the dividend isn't guaranteed until it's declared.  It may have paid the quarterly dividend like clockwork for the last decade, that does not guarantee it will pay this quarter.   Regarding question number 2.  Yield is generally an after the fact calculation.  Dividends are paid out of current or retained earnings.  If the company becomes hot and the stock price doubles, but earnings are relatively similar, the dividend will not be doubled to maintain the prior yield; the yield will instead be halved because the dividend per share was made more expensive to attain due to the increased share price.   As for the calculation, obviously your yield will likely vary from the yield published on services like Google and Yahoo finance.  The variation is strictly based on the price you paid for the share.  Dividend per share is a declared amount.  Assuming a $10 share paying a quarterly dividend of $0.25 your yield is: Now figure that you paid $8.75 for the share. Now the way dividends are allocated to shareholders depends on dates published when the dividend is declared.  The day you purchase the share, the day your transaction clears etc are all vital to being paid a particular dividend.  Here's a link to the SEC with related information: https://www.sec.gov/answers/dividen.htm I suppose it goes without saying but, historical dividend payments should not be your sole evaluation criteria.  Personally, I would be extremely wary of a company paying a 40% dividend ($1 quarterly dividend on a $10 stock), it's very possible that in your example bar corp is a more sound investment. Additionally, this has really nothing to do with P/E (price/earnings) ratios. "What you are looking for is an indicator called the ""Rate of Change (Price)"". It provides a rolling % change in the price over the period you have chosen.  Below is an example showing a price chart over the last 6 months with a 100 day Rate of Change indicator below the price chart." As I write this, the NASDAQ Composite is at 2790.00, down 6.14 points from yesterday. To calculate the percentage, you take 6.14 and divide by yesterday's close of 2796.14 to yield 0.22%. In your example, if SPY drops from 133.68 to 133.32, you use the difference of -0.36 and divide by the original, i.e. -0.36/133.68 = -0.27%. SPY is an ETF which you can invest in that tracks the S&P 500 index. Ideally, the index would have dropped the same percentage as SPY, but the points would be different (~10x higher). To answer your question about how one qualifies a point, it completely depends on the index being discussed. For example, the S&P 500 is a market-capitalization weighted index of the common stock of 500 large-cap US public companies. It is as if you owned every share of each of the 500 companies, then divide by some large constant to create a number that's easily understood mentally (i.e. 1330). The NASDAQ Composite used the same methodology but includes practically all stocks listed on the NASDAQ. Meanwhile, the Dow Jones Industrial Average is a price-weighted index of 30 large-cap companies. It's final value is modified using a divisor known as the Dow Divisor, which accounts for stock splits and similar events that have occurred since a stock has joined the index. Thus, points when referring to an index do not typically represent dollars. Rather, they serve as a quantitative measure of how the market is doing based on the performance of the index constituents. ETFs like SPY add a layer of abstraction by creating an investible vehicle that ideally tracks the value of the underlying index directly. Finally, neither price nor index value is related to volume. Volume is a raw measurement of the total number of shares traded for a given stock or the aggregate for a given exchange. Hope this helps! Simple, there is no magic price adjustment after sales - why do you expect the stock price to change? The listed price of a stock is what someone was willing to pay for it in the last deal that was concluded. If any amount of stock changes ownership, this might have the effect that other people are willing to buy it for a higher price - or not. It is solely in the next buyer's decision what he is willing to pay. Example: if you think Apple stocks are worth 500$ a piece, and I buy a million of them, you might still think they are worth 500$. Or you might see this as a reason that they are worth 505$ now. It helps to put the numbers in terms of an asset. Say a bottle of wine costs 10 dollars, but the price rises to 20 dollars a year later. The price has risen 100%, and your dollars have lost value. Whereas your ten used to be worth 100% of the price of bottle of wine, they now are worth 50% of the risen price of a bottle of wine so they've lost around 50% of their value. Divide the old price by the new inflated price to measure proportionally how much the old price is of the new price. 10 divided by 20 is 1/2 or .50 or 50%. You can then subtract the old price from the new in proportional terms to find how much value you've lost. 1 minus 1/2 or 1.00 minus .50 or 100% minus 50%. With your numbers, look at it this way - You borrowed $50. When the stock is $100, you are at 50% margin.  What's most important, is that there's margin interest charged, so the amount owed will increase regardless of the stock price. When calculating your return or loss, the interest has to be accounted for or your numbers will be wrong. For a small investor, margin rates can run high, and often, will offset much of your potential gain. What good is a $100 gain if you paid $125 in margin interest? Graphs are nothing but a representation of data. Every time a trade is made, a point is plotted on the graph. After points are plotted, they are joined in order to represent the data in a graphical format.  Think about it this way.  1.) Walmart shuts at 12 AM. 2.)Walmart is selling almonds at $10 a pound.  3.) Walmart says that the price is going to reduce to $9 effective tomorrow. 4.) You are inside the store buying almonds at 11:59 PM.  5.) Till you make your way up to the counter, it is already 12:01 AM, so the store is technically shut. 6.) However, they allow you to purchase the almonds since you were already in there.  7.) You purchase the almonds at $9 since the day has changed. 8.) So you have made a trade and it will reflect as a point on the graph. 9.) When those points are joined, the curves on the graph will be created. 10.) The data source is Walmart's system as it reflects the sale to you. ( In your case the NYSE exchange records this trade made). Buying a stock is just like buying almonds. There has to be a buyer. There has to be a seller. There has to be a price to which both agree. As soon as all these conditions are met, and the trade is made, it is reflected on the graph. The only difference between the graphs from 9 AM-4 PM, and 4 PM-9 AM is the time. The trade has happened regardless and NYSE(Or any other stock exchange) has recorded it! The graph is just made from that data. Cheers. If one wants to have a bound on the loss percentages that are acceptable, this is would be a way to enforce that. For example, suppose someone wants to have a 5% stop-loss but doesn't want this to be worse than 10% as if the stock goes down more than 10% then the sell shouldn't happen. Thus, if the stock opened in a gap down 15% one day, this triggers the stop-loss and would exit at too low of a price as the gap was quite high as I wonder how familiar are you with how much a stock's price could change that makes the prices not be as continuous as one would think. At least this would be my thinking on a volatile stock where one may want to try to limit losses if the stock does fall within a specific range. The price-earnings ratio is calculated as the market value per share divided by the earnings per share over the past 12 months. In your example, you state that the company earned $0.35 over the past quarter. That is insufficient to calculate the price-earnings ratio, and probably why the PE is just given as 20. So, if you have transcribed the formula correctly, the calculation given the numbers in your example would be: 0.35 * 4 * 20 = $28.00 As to CVRR, I'm not sure your PE is correct. According to Yahoo, the PE for CVRR is 3.92 at the time of writing, not 10.54. Using the formula above, this would lead to: 2.3 * 4 * 3.92 = $36.06 That stock has a 52-week high of $35.98, so $36.06 is not laughably unrealistic. I'm more than a little dubious of the validity of that formula, however, and urge you not to base your investing decisions on it. Opening - is the price at which the first trade gets executed at the start of the trading day (or trading period). High - is the highest price the stock is traded at during the day (or trading period). Low - is the lowest price the stock is traded at during the day (or trading period). Closing - is the price at which the last trade gets executed at the end of the trading day (or trading period). Volume - is the amount of shares that get traded during the trading day (or trading period). For example, if you bought 1000 shares during the day and another 9 people also bought 1000 shares each, then the trading volume for the day would be 10 x 1000 = 10,000. Stock price = Earning per share * P/E Ratio. Most of the time you will see in a listing the Stock price and the P/E ration. The calculation of the EPS is left as an exercise for the student Investor.