The Performance indicator displays the percentage that the security has increased since the first period displayed. It is then displayed as a positive or negative value. For example, if the Performance indicator is 10, it means that the security's price has increased 10% while a value of -10% means that the security's price has fallen by 10% since the first period displayed.
The Performance indicator displays a security's price performance as a percentage. This is sometimes called a "normalized" chart.