Originally Posted by
tandempower
Well, think about it. If you do some analysis and figure out that you'll make less money on your automotive stocks if ride-sharing companies and other alternatives to car ownership grow, then it makes sense to (short) sell those companies to attempt to drive them out of business, i.e. by driving investors away from them out of fear they'll lose their money if they invest.
I think you're misunderstanding the effects of shorting a stock. Individuals or even large institutions don't have the ability to significantly move stock prices. Investors short stocks they believe are overvalued. They're not shorting to move the stock, rather they're hoping to capitalize on the eventual correction in an over-valued stock. While individual short sellers theoretically have the ability to impact stock prices they also take considerable risks if the company continues to perform well.