You know there are loads of Android apps for alerting on exchange prices, right? SMS could be an option for those without smart phones, but as a smart phone owner I prefer the app.
Sure, I use one of those too. But I have alerts set on 5% or 10% drop, so it doesn't disturb me too often (5% is usual even if there aren't any bad news). But when the price is 5% or 10% already down and I just start to wonder what's happening, it is usually already too late.