From Investopedia :

Understanding Stock Bashers......

"............In most cases, the stock basher will directly benefit by spreading highly negative rumors, hoping that investors will believe the false claims and sell their stock before it fails This allows the basher and their backers to purchase the stock and reap greater gains. While this seems to be the primary motivation for most stock bashing, some analysts also speculate that some bashers are simply former employees or stakeholders in a company pursuing revenge."

for more information.....

https://www.investopedia.com/terms/s/stockbasher.asp