“Anything greater than an 8 percent move in stocks in one day is probably because of something either so fantastic or so bad that taking more than another day to think about it is a good thing,” Paul Tudor Jones, said.
During earnings season you will find many big moves of 8% plus . These are precipitated by earnings surprise or miss or forward guidance. These big moves often signal start of a multi month or year rallies.
New information leads to new moves. If the new information significantly changes the market participants "expectations" about the company then it brings in new set of buyers or leads to selling by existing holders.
Earnings is the most powerful long term driver of stocks. In certain sectors like Biotech future expectations of sales or profit based on drug trial news or FDA approval can lead to big change in market expectations.
If you are looking to find big multi week or month moves in the market then focus on earnings surprises. Every earnings season there are handful of stocks that surprise the market significantly. In most cases these are unknown stocks that enter a growth phase or improve their business margins or productivity and then surprise the market. Market quickly notices these new growth stars and bids them up.
In order to find such opportunities you need to focus on earnings breakout and track them for next 30 to 40 days. Many of those stocs go on to make big move after few days or weeks.