As Sir Isaac Newton said in his First Law of Motion: An object in motion will stay in motion, unless an outside force acts upon it.
That gave rise to the concept of momentum. In the financial markets, price has momentum too. Daryl Guppy, documented in his book about the characteristics of price movement of shares. He verified his obervations with actual results and here are the details:
Sideway
A stock trading within a band (price range) has a 70% chance to move sideways further. This leaves 50% chance to either move up or down. Hence, there is a 15% chance to go up and a 15% to go down.
