Not so sure about traders. I've known a few traders and they...

Not so sure about traders. I've known a few traders and they rarely sell on days of rises. What they do is increase the trailing stop price as the share price rises and will only sell if the price point is breached. Real traders don't typically sell on strong days. Let's not forget there will be investors who either reduce their holdings or might decide they've made enough to meet their objectives and happily sell.