StockVolatilityFifteenDays: Measure 15-Day Stock Volatility in Excel

The StockVolatilityFifteenDays function is a powerful tool in MarketXLS that calculates a stock’s 15-day volatility (standard deviation). By analyzing daily percentage returns over the last 15 trading days, you gain a quick insight into the stock’s short-term price fluctuations. This can help you assess potential risk before making critical trading decisions.

Why Use This Function?

• Analyze risk in your portfolio: Assess whether a particular stock is experiencing higher or lower short-term volatility relative to others.
• Swift volatility checks: Quickly retrieve the standard deviation to gauge daily price swings in your Excel worksheets.
• High-level decision-making: Bridge historical price movements with your trading strategies to help forecast near-term market behavior.
• Ease of automation: By placing this function in your trading models, you can automate risk metrics and screening tasks.

How to Use in Excel

=StockVolatilityFifteenDays(Symbol)

Simply enter the function name in a cell, followed by the desired stock ticker symbol or another valid symbol in quotes (or reference a cell containing that symbol). For example:

• =StockVolatilityFifteenDays("AAPL")
• =StockVolatilityFifteenDays(A2) ? where A2 might contain "MSFT"

MarketXLS will pull the relevant data for the last 15 trading days, calculate daily returns, and then determine the standard deviation of those returns.

Parameters Explained

Example Usage

Basic Examples

1. Direct Symbol Entry
   =StockVolatilityFifteenDays("AAPL")
   • Returns the 15-day volatility (std. dev.) of Apple Inc.’s daily returns.
   • If Apple’s data is unavailable or the symbol is invalid, the function returns "NA".

2. Cell Reference
   Suppose cell B1 contains "TSLA".
   =StockVolatilityFifteenDays(B1)
   • This reads the symbol from cell B1 dynamically.
   • Updates automatically if you change B1’s ticker to another valid symbol.

3. Creating a Quick Volatility Comparison
   Enter in C1: =StockVolatilityFifteenDays(A1)
   Enter in D1: =StockVolatilityFifteenDays(B1)
   • Compare two different stocks side by side.
   • Useful to see which stock is more volatile over the same 15-day window.

Advanced Scenarios

• Integrating with Other Functions:
Combine multiple MarketXLS functions for deeper analysis. For example, you could pair StockVolatilityFifteenDays with StockPrice to compare actual price moves to volatility over time for risk management strategies.

• Portfolio Screening:
In a sheet with multiple tickers listed, apply StockVolatilityFifteenDays across each symbol to identify which positions exhibit higher short-term fluctuations.

• Trading Strategy Insights:
Some traders use short-term volatility as a signal for when to enter or exit positions. Linking this function with conditional formatting can highlight stocks exceeding a certain volatility threshold.

Common Questions and Troubleshooting

• What if the function returns “NA”?
– Your symbol might be invalid, not recognized by the data provider, or your license may be invalid or expired.

• Can I apply different time windows?
– This specific function is fixed to a 15-day window by design. For alternative periods, you would need a function or parameter that accommodates different date ranges.

• How can I interpret the volatility number?
– The function returns the standard deviation as a decimal. For instance, "0.015" indicates a 1.5% daily standard deviation. Some users multiply by 100 to convert it into a percentage.

• Why might there be an insufficient data error?
– If the stock hasn’t been trading long enough or has missing data for the last 15 calendar days, data points can be insufficient. In that case, the function may return “Error: Insufficient data…” or simply “NA.”

By using the StockVolatilityFifteenDays function in MarketXLS, you gain a convenient and fast way to measure short-term risk directly within Excel. This helps you make more informed decisions based on near-term price behavior and volatility trends.