Offer your thoughts or opinion on the input financial query or topic using your financial background.

How can one go short in Uber?
Pay someone a fee to borrow their private Uber shares, then sell those private shares to someone else, then find someone else you can buy their private shares from for less than the net of the proceeds you made selling the borrowed shares you sold plus the fees you've paid to the first person and return your newly purchased shares back to the person you initially borrowed the shares from. On a serious note, Uber is private; there is no liquid public market for the shares so there is no mechanism to short the company.  The valuations you see might not even be legitimate because the company's financials are not public.  You could try to short a proxy for Uber but to my knowledge there is no public "rideshare"/taxi service business similar enough to Uber to be a reasonably legitimate proxy.