Another way of looking at it:<p>Shorting is (roughly given efficient market assumptions) equivalent to buying a put and selling a call at the same strike. If the stock has no chance of going up a lot, the call will be relatively cheap, and so selling the call won&#x27;t change much.<p>Edit: on the other hand if it has low volatility in both directions, then both are cheap, and it&#x27;s a bit more complicated. Buying the put will be cheaper, but shorting will also require less margin because the margin provider will have less risk. (See e.g. <a href="http:&#x2F;&#x2F;openmarkets.cmegroup.com&#x2F;3785&#x2F;understanding-margin-changes" rel="nofollow">http:&#x2F;&#x2F;openmarkets.cmegroup.com&#x2F;3785&#x2F;understanding-margin-ch...</a>).<p>This should cancel out in theory, but might not for various reasons like transaction costs.