What's a Move?
Investors
So, you're an investor? Great. What does this stock price movement mean to you?
FICT Stock
Day | Close Price |
Thursday | $100.00 |
Friday | $102.00 |
The answer is straightforward enough: the stock moved 2% up, and you made $2.
Traders
If you are a trader, it is nice to know that a stock can move 2%; but that doesn't always tell the full story. Here's more of the story of what happened Thursday into Friday.
FICT Stock
Day | Close Price | Low | High |
Thursday | $100.00 | $95.00 | $103.00 |
Friday | $102.00 | $93.00 | $104.00 |
As we can see, for an investor, FICT may be a stock that can move 2% in a day. But for a trader, Friday saw an 11 point move in the stock from bottom to top.
The True Range
What investors consider "noise" in a stock price is therefore what traders consider opportunity.
Consider this real-life example from September / October 2021.
The AMZN chart is from Friday, September 17th - Friday, October 15th.
Day | Close Price |
Fri 9/17 | $3462.52 |
Fri 10/15 | $3409.02 |
From the investor perspective, AMZN moved 53 points in 4 weeks. Yet the trader had multiple 24-hour periods with 100 point moves to exploit!
Calculations
So, does it move?
To find out, we take a simple measurement of a stock's low-to-high price range.
The 1-Day Move
For the one-day look back, we use the previous day's closing price and the low-high for the day. The gap between the lowest and highest of those numbers is the stock's True Range.
Day | Close Price | Low | High |
Wednesday | $93.00 | $91.00 | $93.00 |
Thursday | $100.00 | $95.00 | $103.00 |
Friday | $102.00 | $93.00 | $104.00 |
The True Range for the stock on Thursday is $10 and on Friday is $11. Note how Thursday's True Range considers the gap-up from Wednesday's close at $93 to Thursday's actual low at $95.
So the Thursday 1-day look back calculation (ie after the Thursday close), is taking the min-max of the following data points:
- Wednesday Close
- Thursday low
- Thursday high
The 2-Day Move
Likewise, the two-day look back considers any possible gap up/down from the previous close.
So the Thursday 2-day look back calculation is taking the min-max of the following data points:
- Tuesday Close
- Wednesday low
- Wednesday high
- Thursday low
- Thursday high