How does stock price goes up in the case of bad news and vice versa?

I had this doubt from a very long time . How does stock price goes up in the event of bad news and goes down in the case of good news ?

It maybe discounted to the news already.
What bad news you are referring to?

Whn big institutions intend to buy they spread fake news so retailers sit on the sell side n their quantity gets fulfilled
N vica versa