I was talking about raw trading of the oil itself, but I agree with you that there are many oil proxies in the equity markets, such as refiners, oil service firms, drillers, the big oil companies, etc. Let’s not even get into things like mutual funds, exchange-traded funds, hedge funds, etc.
But you can only short a small percentage of a market before it moves, and then you have to exit profitably at risk of getting caught up in a short-covering rally. Timing is critical, you can never trust that other investors will act as you desire, and the larger the target is that you’re trying to short, the harder it becomes. Successfully shorting things like currencies these days, George Soros-style against the British Pound from back whenever, is almost impossible to pull off. To do it surreptitiously without raising alarm bells somewhere is even harder still.
But alas, I have never actually done this myself, so I am admittedly not very well versed on the daunting mathematics of it (I’ve never understood the pricing of options, for example). I’m a very busy person and have to choose very carefully what to spend time on. I come here mostly to learn, so instead of throwing shade with vacuous cliches (“text book reply”, really? As opposed to what, your “street smarts”? :)), I invite you to teach me something about this if you are so learned in it. If it’s too long for a comment, at least provide a link so I know where you are getting your information and inspiration from.