Unusual trading patterns & hedging

This question is for all different forms of instruments- stocks, NFO , commodities, currency etc.

Manyatimes its easy to predict based on global news that a stock or instrument will go up or down based on sentiments, has anyone observed that a stock showed reverse patern despite global/local cues?

What happens during RBI announcements , elections etc?

How do investors hedge such risk and how does hedging work?