Trends/Volatility and bands

Historical volatility

How much the price has been moving recently, as an annual percent, calculated from daily returns.

Volatility and bandsBest on 6M, 1Y, 3YAlso called realized volatility

Illustration of the historical volatility shape. It is a sketch, not real price data.

What it shows

Historical volatility measures how much a stock's returns have varied. It takes the standard deviation of the daily percent changes over a window, and scales it to a year. A higher number means bigger swings.

It describes the past. A volatility of 30% means that, if the same pace continued, the stock would typically move about 30% over a year in either direction.

How we find it

The same code that draws it on your chart follows these steps, with the same result every time.

Compute daily log returns: ln(close ÷ previous close).
Take the standard deviation over the last 20 bars.
Multiply by the square root of 252 to scale it to a year.
Plot it under the price.

Starting values: Window 20 bars; Annualizing × √252. These are proposed and will be tuned on real price data before launch.

How to read it

The panel shows annual volatility in percent.
A spike shows a stretch of large moves.
A low line shows a quiet stretch.

Status labels you may see

Label	What it means
Low	In the lowest third of the stock's own history.
Medium	Middle third.
High	Highest third.

What cancels it

Nothing cancels it.

What traders check next

How it compares with the stock's own average.
What caused spikes.
Whether volatility is rising or falling.

Limits

It is backward-looking.
One big day can raise it for 20 bars.
Daily and weekly versions differ.

Try it in forecastviz

Open any ticker and choose Volatility and bands → Historical volatility in the left menu.
Switch between 6M, 1Y, 3Y to see how the picture changes.
Compare with Volatility percentile and Average true range on the same chart.

Open on a ticker

Questions

Is this the same as implied volatility?

No. Implied volatility comes from option prices. This is calculated from past prices.

Why annual?

So stocks with different data frequency can be compared.