> Why do market makers buy stock for delta hedging? How do they figure out how much stock to buy? From https://www.bloomberg.com/opinion/articles/2021-01-25/th

> Why do market makers buy stock for delta hedging? How do they figure out how much stock to buy? From https://www.bloomberg.com/opinion/articles/2021-01-25/the-game-never-stops#footnote-5 https://www.bloomberg.com/opinion/articles/2021-01-25/the-ga...: The market maker has sold you an option that goes up in value as the stock goes up. The more the stock goes up, the more the market maker owes you. It hedges this by buying something else that goes up in value as the stock goes up—specifically, stock. Its option pricing model—the Black-Scholes formula or a related model—tellsit how much stock to buy; that output is a number called “delta” and ordinarily expressed as a percentage. Delta is the sensitivity of the option price to the stock price; the higher the delta, the more the option behaves like stock. The more in-the-money the option—for a call option, the higher the stock price is relative to the strike price—the higher the delta will be. A loose, nontechnical, incorrect but still sometimes helpful way to think about delta is as “the probability that an option will end up in the money.” A 100-delta option is so far in the money that it is sure to convert into stock, so it's just stock. A 0-delta option is so far out of the money that it can’t possibly convert into stock, so it’s just worthless. A 50-delta option is roughly at-the-money—a $50-strike call when the stock is trading at $50—and could go either way. The more stock-like an option is, the more stock the market maker will buy to hedge it. Here,Bloomberg’s OV page computes a 37.57% delta for the Jan. 29 $50 call as of last Tuesday; I rounded up for ease of use. If you are remotely interested in these kinds of things I can heartily recommend reading Matt Levine (https://www.bloomberg.com/opinion/authors/ARbTQlRLRjE/matthew-s-levine https://www.bloomberg.com/opinion/authors/ARbTQlRLRjE/matthe...). He's at the same time educating and entertaining and what is more leaves out all the bile and negativity that is connected to these topics in other places. Gamestop is covered in recent issues.