The Price Alert is triggered based on the daily price change % of the stocks in your portfolio or watchlist. You can choose to receive alerts if the price change is more than 5% and/or 10%. 

You can also add alerts for stocks touching or nearing their 52-week high/low, as shown below.

You can set the frequency of these alerts to 15 minutes, 30 minutes, 1 hour, or a day, as shown below. These alerts are sent to your registered email.