Price Ratio (Relative Strength)
The Price Ratio (or relative strength - comparative) serves a similar purpose to Price Comparison - it compares the performance of one stock relative to another (or to an index). Some traders use the Price Ratio as a general tool to select outperforming stocks.
Price Ratio is calculated by dividing the closing price of the first stock by the second.
Unlike Price Comparison, Price Ratio is plotted in a separate indicator panel.
Example
Microsoft is charted with
the Price Ratio to the Dow Jones Industrial Average,
Price Comparison to DJIA is shown on the
price chart to illustrate:
- The Price Ratio is positive when MSFT is above DJIA on the price chart.
- The ratio is negative when MSFT falls below the DJIA.

Note how MSFT has under-performed relative to the Dow since March 2000.
Setup
To set up the Price Ratio indicator:
- Open the Indicator Panel
- Select Price Ratio in the left column
- Select the comparative security or index from the drop-down menu
- Select Daily, Weekly or Monthly from the center panel
- Select Apply to Project or Apply to Securityfrom the
center panel.
Apply to Project applies the indicator to all securities in the current project.
Apply to Security applies the indicator to the current security only. - Save the settings using ">".
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Formula
The Price Ratio is calculated using the ratio of closing price to
that of another security, on the first day of the chart.
This means that the starting point of the Price Ratio will vary according
to the Time Period selected. The line may appear to move if you change
time periods; but the slope remains the same.
Tip
Settle on one or two standard time periods to be used when viewing Price Ratios (eg. 3 Years - Weekly; 6 Months - Daily).
The steps required to calculate the Price Ratio are best illustrated by an example: Calculate the Price Ratio of IBM to the Dow Jones Industrial Average (DJI)-
- Calculate the Inverse Ratio on Day 1: DJI divided by IBM.
- Divide IBM by DJI each day
- Then multiply step 2 by the Inverse Ratio in step 1
- The Price Ratio then reduces the start to zero by subtracting 1 (from step 3).
Example
| Day | IBM | DJI | Inverse Ratio (DJI / IBM) |
IBM / DJI | IR* IBM/DJI | Price Ratio |
| 1 | 8.00 | 4000 | 500 | 0.002000 | 1.000000 | 0.000000 |
| 2 | 7.95 | 4020 | 0.001978 | 0.988806 | -0.011194 | |
| 3 | 8.30 | 4010 | 0.002070 | 1.034913 | 0.034913 |
Note: Metastock ® use a different formula to normalize to zero. They calculate the ratio in step 2 and then subtract the ratio on day 1 from each subsequent day. The results are similar.
