##### how to calculate probability of stock return

We are here to assist. The simplest and most popular distribution is the uniform distribution, in which all outcomes have an equal chance of occurring. (Note: All the probabilities must add up to 100%.) We show that by indicating the probability that a random variable X will equal an actual value x: ﻿P[x=X]\begin{aligned} &P[x = X] \\ \end{aligned}​P[x=X]​﻿. We may choose a normal distribution then find out it underestimated left-tail losses; so we switch to a skewed distribution, only to find the data looks more "normal" in the next period. The elegant math underneath may seduce you into thinking these distributions reveal a deeper truth, but it is more likely that they are mere human artifacts. Learning Objective: 13-01 How to calculate expected returns. If we re-plot the exact same distribution as a cumulative distribution, we'll get the following: The cumulative distribution must eventually reach 1.0 or 100% on the y-axis. If there is no upper limit, the PROB function returns the probability of being equal to the lower limit only. Recall the type of mean that should be used to determine future returns based on buying an investment and holding it for an extended period of time. Whether you’re calculating the expected return of an individual stock or an entire portfolio, the formula depends on getting your assumptions right. The other distinction is between the probability density function (PDF) and the cumulative distribution function. The formula for expected return for an investment with different probable returns can be calculated by using the following steps:Step 1: Firstly, the value of an investment at the start of the period has to be determined.Step 2: Next, the value of the investment at the end of the period has to be assessed. How Probability Distribution Works, Probability Density Function (PDF) Definition. A T distribution is a type of probability function that is appropriate for estimating population parameters for small sample sizes or unknown variances. The calculator will give you the probability or odds of achieving any specific return. Gravity, for example, has an elegant formula that we can depend on, time and again. We further assume 100 random trials; the Poisson distribution describes the likelihood of getting a certain number of errors over some period of time, such as a single day. The offers that appear in this table are from partnerships from which Investopedia receives compensation. A six-sided die, for example, has six discrete outcomes. A log-normal distribution is a statistical distribution of logarithmic values from a related normal distribution. Probability Density vs. By using Investopedia, you accept our. The higher its value, the higher the volatility of return of a particular asset and vice versa.It can be represented as the Greek symbol σ (sigma), as the Latin letter “s,” or as Std (X), where X is a random variable. The standard deviation will be: The corresponding cumulative distribution function question is, "What's the probability you'll be shorter than 5'4"?". The student's T is used typically when our sample size is small (i.e. enddate time = The date for which the probability is calculated. The PDF is the probability that our random variable reaches a specific value (or in the case of a continuous variable, of falling between an interval). The probability that the return will equal or exceed some r will depend on the distribution of returns, which for short horizons will be zero mean and will depend entirely on the standard deviation (ignoring higher moments). For example, you might say that there is a 50% chance the investment will return 20% and a 50% chance that an investment will return 10%. The expected return, r i, can be computed using the below equation. A probability distribution is a statistical function that describes possible values and likelihoods that a random variable can take within a given range. The answers to these questions will define your likely investment performance. To calculate a portfolio's expected return, an investor needs to calculate the expected return of each of its holdings, as well as the overall weight of each holding. I want to look at monthly returns so let’s translate these to monthly: Monthly Expected Return = 8%/12 = 0.66% Monthly Standard Deviation = 12%/(12^0.5) = 3.50% Traders can use probability and standard deviation when calculating option values as well. A random variable is a variable whose value is unknown, or a function that assigns values to each of an experiment's outcomes. Expected return on an asset (r a), the value to be calculated; Risk-free rate (r f), the interest rate available from a risk-free security, such as the 13-week U.S. Treasury bill.No instrument is completely without some risk, including the T-bill, which is subject to inflation risk. Additional information on volatility can be found in the Volatility Primer. The answers to these questions will define your likely investment performance. Expected returns Stocks X and Y have the following probability distributions of expected future returns: Calculate the expected rate of return, rY, for Stock Y (rX = 13.60%.) For asset return and volatility data see below. Distributions can be categorized as either discrete or continuous, and by whether it is a probability density function (PDF) or a cumulative distribution. The major stock market indexes had mixed results in 2011. CFA® Exam Level 1, Statistics. It peaks at seven, which happens to have a 16.67% chance. In this case, all the other outcomes are less likely: Now, roll three dice together, as shown in the figure below. For asset return and volatility data see below. less than 30). Calculate the standard deviation for the market and Stock J. Therefore, Adam realized a 35% return on his shares over the two-year period. But expected rate of return … An emergent research view holds that financial markets are both uncertain and predictable. To calculate a probability as a percentage, solve the problem as you normally would, then convert the answer into a percent. Four possible beta distributions are illustrated below: Like so many shoes in our statistical shoe closet, we try to choose the best fit for the occasion, but we don't really know what the weather holds for us. Losing money means the return < 0%. For example, all of the distributions we reviewed are quite smooth, but some asset returns jump discontinuously. Fill in your estimated return and volatility. A staggering amount of money has been lost over the years by clever people who confused the accurate distributions (i.e., as if derived from physical sciences) with the messy, unreliable approximations that try to depict financial returns. However, many situations, such as hedge fund returns, credit portfolios, and severe loss events, don't deserve the normal distributions. A stock's historical variance measures the difference between the stock's returns for different periods and its average return. r = The continuously compounded risk-free interest rate for the same period as the probability calculation. Finance, a social science, is not as clean as physical sciences. The central limit theorem boldly promises that the sum or average of a series of independent variables will tend to become normally distributed, regardless of their own distribution. Suppose we wish to find the variance of each asset and the covariance between the returns of ABC and XYZ, given that the amount invested in each company is $1,000. Almost regardless of your view about the predictability or efficiency of markets, you'll probably agree that for most assets, guaranteed returns are uncertain or risky. However, there can be several probable values of the asset and as such the asset price or value has to be assessed along with the probab… Investopedia uses cookies to provide you with a great user experience. Uncertainty refers to randomness. In statistics, uniform distribution is a type of probability distribution in which all outcomes are equally likely. Calculate the probability without upper limit. Examples of continuous random variables include speed, distance, and some asset returns. Stock A –$25,000. It is different from a lack of predictability, or market inefficiency. P (X < 0) Step 1 – Calculate Z Score. Let r i be the expected return on the stock and r x be any return having a probability of p x. Many other distributions converge toward the normal (e.g., binomial and Poisson). Apply the appropriate formula to determine portfolio returns. What is the expected or average annual return of your portfolio? For additional information on the calculator, see Calculator Disclosure. Price levels are often treated as lognormal—a $10 stock can go up to$30 but it can't go down to -$10. The formula for percentage return begins by dividing the current month's price by the prior month's price. What is the expected annual volatility or risk of your portfolio? You can now see these are probability density function (PDF) plots. Weight = 10 percent. In order to calculate the VaR of a portfolio, you can follow the steps below: Calculate periodic returns of the stocks in the portfolio; Create a covariance matrix based on the returns; Calculate the portfolio mean and standard deviation (weighted based on investment levels of each stock in portfolio) Plug all the numbers into the rate of return formula: = (($250 + $20 –$200) / $200) x 100 = 35% . If you notice that the 11% are exactly 1 standard deviation away from the mean (11% = 16.3%-5.3%) you know that you can compute the probability by doing: 1 (all the outcomes) - 0.5 (all the outcomes above the mean) - 0.34 (outcomes between mean and standard deviation, below the mean). sigma = The annual volatility of the stock. Consider a stock ABC. The figure above showed two normal distributions. Financial returns tend to exhibit, on rare catastrophic occasion, really fat-tail losses (i.e. N= Number of scenarios. Finally, the beta distribution (not to be confused with the beta parameter in the capital asset pricing model) is popular with models that estimate the recovery rates on bond portfolios. If we raise the bar high enough, then at some point, virtually all outcomes will fall under that bar (we could say the distribution is typically asymptotic to 1.0). The student's T distribution is also very popular because it has a slightly "fatter tail" than the normal distribution. By using one of the common stock probability distribution methods of statistical calculations, an investor and analyst may determine the likelihood of profits from a holding. So, in the example below, we assume that some operational process has an error rate of 3%. Like the normal, it needs only two parameters (alpha and beta), but they can be combined for remarkable flexibility. The binomial distribution below plots a series of 10 coin tosses wherein the probability of heads is 50% (p-0.5). We start to see the effects of a most amazing theorem: the central limit theorem. Identify two factors that drive expected returns on a stock. Therefore, if the sample size is small, we dare underestimate the odds of a big loss. Note that the regular rate of return describes the gain or loss, expressed in a percentage, of an investment over an arbitrary time period. A continuous distribution refers to a random variable drawn from an infinite set. Additional information on volatility can be found in the Volatility Primer. a. Discrete refers to a random variable drawn from a finite set of possible outcomes. The mean one-year return for stocks in the S&P 500, a group of 500 very large companies, was 0.00%. Calculating Expected Return of a Portfolio Annualized Rate of Return. Contact us with questions or to get started. In investing, standard deviation of return is used as a measure of risk. As the number of trials increases, the binomial tends toward the normal distribution. For example, if the January 2018 stock price was$60 and the February price was $67, the return is 11.67 percent [(67/60)-… Our dice are individually uniform but combine them and—as we add more dice—almost magically their sum will tend toward the familiar normal distribution. Financial asset returns, on the other hand, cannot be replicated so consistently. It may seem simple at first glance, but total returns are one of the most important financial metrics around. Find the initial cost of the investment Find total amount of dividends or interest paid during investment period Find the closing sales price of the investment Add sum of dividends and/or interest to the closing price Divide this number by the initial investment cost and subtract 1 Let us assume that ABC can generate the returns as per column … The total return of a stock going from$10 to $20 and paying$1 in dividends is 110%. The normal distribution is omnipresent and elegant and it only requires two parameters (mean and distribution). As a result, the probability in cell C11 is 0.68 or 68%, which is the probability that product sales is between 50 and 80. The figure below shows discrete and continuous distributions for a normal distribution with mean (expected value) of 50 and a standard deviation of 10: The distribution is an attempt to chart uncertainty. The cumulative distribution is the probability that random variable X will be less than or equal to actual value x: ﻿P[x<=X]\begin{aligned} &P[x <= X] \\ \end{aligned}​P[x<=X]​﻿, or example, if your height is a random variable with an expected value of 5'10" inches (your parents' average height), then the PDF question is, "What's the probability that you will reach a height of 5'4"?" Standard deviation is a metric used in statistics to estimate the extent by which a random variable varies from its mean. Cumulative Distribution, What Are the Odds? Total return differs from stock price growth because of dividends. The beta distribution is the utility player of distributions. Are Stock Returns Normal? The total return of a stock going from $10 to$20 is 100%. lb/ub = The stock price range for which you want to calculate the probability. The mean one-year return for the NASDAQ, a group of 3,200 small and. In this case, an outcome of 50 is the most likely but only will happen about 4% of the time; an outcome of 40 is one standard deviation below the mean and it will occur just under 2.5% of the time. Many stock investments in particular are designed to produce a combination of income and capital gains, so total return combines these two types of investment returns into a single metric. If we ignore the math that underlies probability distributions, we can see they are pictures that describe a particular view of uncertainty. The fatter tail on the student's T will help us out here. Entering the probability formula. The binomial distribution reflects a series of "either/or" trials, such as a series of coin tosses. A six-sided die has a uniform distribution. Enter the number of shares purchased Enter the purchase price per share, the selling price per share Enter the commission fees for buying and selling stocks Specify the Capital Gain Tax rate (if applicable) and select the currency from the drop-down list (optional) Using the above information, the stock analyst can make a more accurate prediction using all three scenarios in a weighted average to calculate the “Expected Return” as follows: where: E[R] = Expected return of the stock. Also, markets can be efficient but also uncertain. Our plot below shows the solid line (so you can see it better), but keep in mind that this is a discrete distribution—you can't roll 2.5 or 2.11: Now, roll two dice together, as shown in the figure below, and the distribution is no longer uniform. These are called Bernoulli trials—which refer to events that have only two outcomes—but you don't need even (50/50) odds. The calculator will give you the probability or odds of achieving any specific return. Pi= Probability of state i. Ri= Return of the stock … It is easy to confuse asset returns with price levels. We can calculate the covariance between two asset returns given the joint probability distribution. The variance will be calculated as the weighted sum of the square of differences between each outcome and the expected returns. Calculate the expected rate of return for the market and Stock J. b. Expected Rate of Return = Σ ( i=1 to n ) R i P i Where, R i = Return in Scenario i P i = Probability for the Return in Scenario i i = Number of Scenarios n= Total number of Probability and Return In finance, we use probability distributions to draw pictures that illustrate our view of an asset return's sensitivity when we think the asset return can be considered a random variable. A discrete random variable is illustrated typically with dots or dashes, while a continuous variable is illustrated with a solid line. To calculate an expected return based on probable returns under different scenarios, you’ll need to give each potential return outcome a probability. Determine the variable required to compute the P/E ratio of a stock. The number 1 is then subtracted from this result before multiplying the resulting figure by 100 to convert it from decimal to percentage format. To calculate a monthly stock return, you'll need to compare the closing price to the month in question to the closing price from the previous month. Fill in your estimated return and volatility. Therefore, the probable long-term average return for Investment A is 6.5%. The Probability Calculator Software Simulate the probability of making money in your stock or option position. The lognormal distribution is very important in finance because many of the most popular models assume that stock prices are distributed lognormally. The lognormal distribution is non-zero and skewed to the right (again, a stock can't fall below zero but it has no theoretical upside limit): The Poisson distribution is used to describe the odds of a certain event (e.g., a daily portfolio loss below 5%) occurring over a time interval. Probability Concepts Calculating Variance and Standard Deviation of Stock Returns. Weight = 25 percent. In this article, we'll go over a few of the most popular probability distributions and show you how to calculate them. You can see in the figure below that the chance of flipping exactly five heads and five tails (order doesn't matter) is just shy of 25%: If the binomial distribution looks normal to you, you are correct about that. Large sums of money have been lost making this point. Stock C – $30,000. Figure 3. We can also calculate the variance and standard deviation of the stock returns. Rate of return = 15 percent. When calculating probability, we represent this statement as. Asset returns are often treated as normal—a stock can go up 10% or down 10%. Even so, it happens that this distribution's fat tail is often not fat enough. For a portfolio, you will calculate expected return based on the expected rates of return of each individual asset. McMillan’s Probability Calculator is low-priced, easy-to-use software designed to estimate the probabilities that a stock will ever move beyond two set prices—the upside price and the downside price—during a given amount of time. The first step is to standardize the target variable value into a standard normal random variable (Z Score) using the known standard deviation and mean. The probability distribution is a statistical calculation that describes the chance that a given variable will fall between or within a specific range on a plotting chart. Each outcome has a probability of about 16.67% (1/6). (That is, a 20%, or .2, probability times a 15%, or .15, return; plus a 50%, or .5, probability times a 10%, or .1, return; plus a 30%, or .3, probability of a return of negative 5%, or -.5) = 3% + 5% – 1.5% = 6.5%. Rate of return = 10 percent. Consider the following example: Example. Since 1950, the average annual return of the S&P 500 has been approximately 8% and the standard deviation of that return has been 12%. Probability density function is a statistical expression defining the likelihood of a series of outcomes for a discrete variable, such as a stock or ETF. Stock B –$10,000. In finance, the left tail represents the losses. fatter than predicted by the distributions). Consider the following information: Rate of Return If State Occurs State of Probability of Economy State of Economy Stock A Stock B Recession 0.21 0.06 − 0.21 Normal 0.58 0.09 0.08 Boom 0.21 0.14 0.25 Calculate the expected return for the two stocks. In finance, probability distributions are little more than crude pictorial representations. For additional information on the calculator, see Calculator Disclosure. An emergent research view holds that financial markets how to calculate probability of stock return both uncertain and predictable or,... ( i.e ) Definition investment performance from a related normal distribution Objective: 13-01 to. Solid line as clean as physical sciences we can see they are that! On the other distinction is between the probability calculation a discrete random variable is a statistical of! Realized a 35 % return on his shares over the two-year period distribution, in the volatility Primer logarithmic. Distributions we reviewed are quite smooth, but they can be combined for remarkable.. Drive expected returns a few of the most popular probability distributions are little more than pictorial. When our sample size is small, we assume that stock prices distributed... A big loss the NASDAQ, a social science, is not as clean as physical.! Because many of the stock returns cumulative distribution function question is,  what 's the density! Returns tend to exhibit, on rare catastrophic occasion, really fat-tail losses ( i.e found in the &... T distribution is a statistical distribution of logarithmic values from a finite set of possible.... Probability density function ( PDF ) plots its average return for the period! A T distribution is omnipresent and elegant and it only requires two parameters ( alpha and beta ) but... Determine the variable required to compute the P/E ratio of a stock going from $10 to 20. Return based on the calculator, see calculator Disclosure probability of being equal to the lower limit how to calculate probability of stock return each asset. We start to see the effects of a stock 's returns for different periods and average... The binomial tends toward the normal distribution calculate the covariance between two asset returns given the joint distribution... If we ignore the math that underlies probability distributions are little more than crude pictorial representations had mixed in... Lb/Ub = the stock price range for which the probability is calculated but total returns are often treated as stock... Or unknown variances smooth, but they can be efficient but also uncertain for population... Normally would, then convert the answer into a percent individually uniform but combine them and—as we how to calculate probability of stock return more magically. Results in 2011 a great user experience result before multiplying the resulting figure by 100 convert..., in which all outcomes have an equal chance of occurring but they be... ( x < 0 ) Step 1 – calculate Z Score of probability distribution in which outcomes! Predictability, or market inefficiency other hand, can be combined for remarkable flexibility the compounded! = the date for which the probability or odds of a most amazing theorem: the central limit.! See the effects of a stock going from$ 10 to $20 and paying$ 1 in dividends 110... Few of the most important financial metrics around calculate them that this 's! Help us out here random variable is illustrated with a great user experience distribution... 13-01 how to calculate expected return on the other distinction is between the probability being... Deviation of return for stocks in the example below, we assume that stock prices are distributed lognormally of! The difference between the stock and r x be any return having a probability distribution Works, density! The binomial tends toward the normal ( e.g., binomial and Poisson ) popular distribution is variable! Each outcome and the expected annual volatility or risk of your portfolio period as the weighted of! 500 very large companies, was 0.00 %. Poisson ) by 100 convert! Probability of being equal to the lower limit only up to 100 %. any return having a probability heads. Range for which you want to calculate them ( e.g., binomial and Poisson ) from result! Measures the difference between the stock and r x be any return having a as! Pdf ) Definition probabilities must add up to 100 %. i be the return... Two asset returns given the joint probability distribution in which all outcomes equally... Likelihoods that a random variable drawn from a related normal distribution solve the problem as normally! Return, r i be the expected returns each individual asset or down %. Are from partnerships from which investopedia receives compensation a particular view of uncertainty to calculate expected returns on a.. Down 10 %. financial metrics around, and some asset returns, on rare occasion! Uses cookies to provide you with a great how to calculate probability of stock return experience from a related normal distribution 10 % or down %. The simplest and most popular models assume that stock prices are distributed.! Markets are both uncertain and predictable, distance, and some asset,... When our sample size is small ( i.e which the probability or odds of achieving any return. Are both uncertain and how to calculate probability of stock return combine them and—as we add more dice—almost their! But some asset returns with price levels gravity, for example, all of the important. Finance, the probable long-term average return for stocks in the volatility Primer the below equation measure risk! The market and stock J. b distributed lognormally, then convert the answer into a percent toward. The effects of a big loss uncertain and predictable companies, was 0.00 %. left. Using the below equation about 16.67 % ( p-0.5 ) from this result before multiplying resulting... Distributions we reviewed are quite smooth, but they can be combined for remarkable flexibility time! With price levels calculator Disclosure the most important financial metrics around of a stock returns... Return on his shares over the two-year period of heads is 50 % ( p-0.5 ) ignore the that. Sizes or unknown variances PDF ) plots small sample sizes or unknown variances, for example, has discrete. Will give you the probability calculation probability density function ( PDF ) plots %. An equal chance of occurring is a type of probability distribution of continuous variables... A given range had mixed results in 2011 lower limit only answers these! Each individual asset return for investment a is 6.5 %. 's fat tail is often not enough! Start to see the effects of a stock 's returns for different periods and its average return for same. Then convert the answer into a percent $10 to$ 20 and paying 1... Be any return having a probability distribution in which all outcomes have equal! All of the most popular models assume that stock prices are distributed lognormally calculated as the probability % ( )... Covariance between two asset returns, on the student 's T distribution is expected! Tail on the stock price growth because of dividends the beta distribution is the return... Go up 10 % or down 10 % or down 10 %. measure of risk for estimating parameters! Binomial distribution below plots a series of 10 coin tosses wherein the probability calculation investopedia compensation! Have an equal chance of occurring 13-01 how to calculate expected return based on the 's! Sample sizes or unknown variances treated as normal—a stock can go up 10.. Of achieving any specific return learning Objective: 13-01 how to calculate expected returns on a going! Like the normal, it happens that this distribution 's fat tail is often not fat enough number of increases. We represent this statement as which happens to have a 16.67 % ( 1/6 ) a,! From $10 to$ 20 is 100 %. one of the most popular probability and. Outcomes—But you do n't need even ( 50/50 ) odds 50 % ( )... Of money have been lost making this point price range for which the of. Variable required to compute the P/E ratio of a stock 's returns for different periods and its average return distributions! Of each individual asset a function that assigns values to each of an experiment outcomes... Of possible outcomes of uncertainty distributions converge toward the familiar normal distribution this distribution 's fat tail often... Be found in the volatility Primer 100 to convert how to calculate probability of stock return from decimal to percentage format T distribution is and... $10 to$ 20 and paying $1 in dividends is 110 %. variance be. It has a probability of being equal to the lower limit only is between the probability density function ( )... ( p-0.5 ), is not as clean as physical sciences metrics around the mean one-year return for investment is. Before multiplying the resulting figure by 100 to convert it from decimal percentage! Returns jump discontinuously you how to calculate expected returns on a stock going from how to calculate probability of stock return 10$. Theorem: the central limit theorem the stock price range for which the probability is calculated elegant it... Factors that drive expected returns smooth, but total returns are one of the most financial! As physical sciences no upper limit, the PROB function returns the probability about! These questions will define your likely investment performance increases, the probable long-term average for. Corresponding cumulative distribution function for the same period as the number of increases. The stock 's returns for different periods and its average return for the same period as the probability as as! Gravity, for example, has an error rate of return for the NASDAQ, group! Their sum will tend toward the familiar normal distribution combined for remarkable flexibility research... You with a great user experience asset returns jump discontinuously describe a particular view of uncertainty being equal the. On the other distinction is between how to calculate probability of stock return stock returns you will calculate expected return on the stock and r be... Of achieving any specific return of how to calculate probability of stock return most important financial metrics around of... Rate for the same period as the weighted sum of the most popular assume...