
Portfolio Risks and Returns  Stock Risks
Types of Risks
Here are some risks associated with investing in the stock markets:
 Systematic risk  also known as market risk, this is the potential for the entire market to decline. Systematic risk cannot be diversified away.
 Unsystematic risk  the risk that any one stock may go down in value, independent of the stock market as a whole. This risk may be minimized through diversification. This also incorporates business risk and event risk, as described in the "Bond Risks" section.
 Other risks  opportunity risk and liquidity risk (as described in the "Bond Risks" section) may also apply to stocks in a portfolio.
Quantitative Analysis
One of the concepts used in risk and return calculations is standard deviation, which measures the dispersion of actual returns around the expected return of an investment. Since standard deviation is the square root of the variance, this is another crucial concept to know. The variance is calculated by weighting each possible dispersion by its relative probability (take the difference between the actual return and the expected return, then square the number).
The standard deviation of an investment's expected return is considered a basic measure of risk. If two potential investments had the same expected return, the one with the lower standard deviation would be considered to have less potential risk.
Standard deviation takes into account both systematic risk and unsystematic risk and is considered to be a measure of an investment's total risk.
Risk measures
There are three other risk measures used to predict volatility and return:
 Beta  measures stockprice volatility based solely on general market movements. Beta is a relative measure of systematic risk. Typically, the market as a whole is assigned a beta of 1.0. So, a stock or a portfolio with a beta higher than 1.0 is predicted to have a higher risk, and potentially, a higher return than the market. Conversely, if a stock (or fund) had a beta of 0.85, this would indicate that if the market increased by 10%, this stock (or fund) would likely return only 8.5%. However, if the market dropped 10%, this stock would likely drop only 8.5%.
 Alpha  measures stockprice volatility based on the specific characteristics of the particular security. As with beta, the higher the number, the higher the risk.
 Sharpe ratio  a more complex measure that uses the standard deviation of a stock or portfolio to measure volatility. It is a measure of riskadjusted return. This calculation measures the incremental reward of assuming incremental risk. The larger the Sharpe ratio, the greater the potential return. The formula is: Sharpe Ratio = (total return minus the riskfree rate of return) divided by the standard deviation of the portfolio.
Look Out! Of course, the reverse of "the larger the Sharpe ratio, the greater the return," is that the lower the ratio, the lower the potential return. If a security\'s Sharpe ratio were equal to "0", there would be no reward for taking on the higher risk, and the investor would be better off simply holding Treasuries (whose return is equal to the riskfree return component of the equation). 
RiskReduction Strategies for Stocks

Bonds & Fixed Income
Find The Highest Returns With The Sharpe Ratio
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Fundamental Analysis
How Investment Risk Is Quantified
FInancial advisors and wealth management firms use a variety of tools based in Modern portfolio theory to quantify investment risk. 
Active Trading Fundamentals
Measuring And Managing Investment Risk
Risk is inseparable from return. Learn more about these measures and how to balance them. 
Investing
Measure Your Portfolio's Performance
Learn three ratios that will help you evaluate your investment returns. 
Mutual Funds & ETFs
PRHSX: T. Rowe Price Health Sciences Fund Risk Statistics Case Study
Examine the risk metric of the T. Rowe Price Health Sciences Fund. Analyze beta, capture ratios and standard deviation to assess volatility and systematic risk. 
Fundamental Analysis
How To Measure Your Portfolioâ€™s Performance
The first tool for assessing portfolio performance while considering risk was the Treynor measure. 
Fundamental Analysis
The Capital Asset Pricing Model: An Overview
CAPM helps you determine what return you deserve for putting your money at risk. 
Investing Basics
Mitigating Downside With The Sortino Ratio
Differentiate between good and bad volatility with the Sortino Ratio. 
Active Trading Fundamentals
5 Ways To Rate Your Portfolio Manager
Investopedia explains: These five performance ratios will help you measure how good your money manager is at increasing the value of your portfolio. 
Markets
The Uses And Limits Of Volatility
Check out how the assumptions of theoretical risk models compare to actual market performance.

RiskAdjusted Return
A concept that refines an investment's return by measuring how ... 
Downside Deviation
A measure of downside risk that focuses on returns that fall ... 
Systematic Risk
The risk inherent to the entire market or entire market segment. ... 
International Beta
Better known as "global beta", international beta is a measure ... 
Market Risk
The possibility for an investor to experience losses due to factors ... 
Treynor Index
A measure of riskadjusted performance of an investment portfolio. ...

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