Identical or similar parcel of shares in market depth Pre-Open, page-2

There are plenty of reasons, both legal and illegal.

A legal reason may be that the trader has set up trigger algos which notify or release a buy/sell order into market once the price is hit.

An illegal reason may be someone doing a ladder attack or hedge funds buying and selling amongst themselves to drive the share price lower. Its usualy to get some paper hands to sell at loss so that hedn buy in cheaper.

in the end, always remember the reason why you bought the stock. If the fundamentals are strong and your research sound then sooner or later you will reap the rewards. Don't give in to your psychology,.