What Happens After You Sell: Market Makers and Delta Hedging

Nobody took the other side of your view

You sell a put because you think the stock will hold above the strike. It is tempting to imagine someone on the other side who thinks it will not.

Usually there is no such person. The immediate counterparty is a market maker, and a market maker quoting both sides of a contract is not taking a directional position. They are running a business whose product is immediacy: they stand ready to buy or sell at any moment, and they charge for it through the spread.

Understanding what they do next explains several things that otherwise look arbitrary — why some contracts quote tightly and others do not, why liquidity evaporates exactly when you want it, and why the "someone must be wrong" framing of your trade is mistaken.

The problem they have

A market maker buys your put. They now hold a position that gains value if the stock falls. They did not want that exposure; they wanted the spread.

So they neutralise it. If the put they bought has a delta of roughly −0.30, the position behaves like being short 30 shares. To cancel that, they buy about 30 shares of the underlying.

Now the combined position is roughly indifferent to small moves in the stock. Whatever the shares lose, the option gains, and vice versa. The maker has kept the spread and disposed of the direction.

That is delta hedging, and it happens more or less instantly and automatically.

Why it has to be continuous

Delta is not constant. It changes as the stock moves, as time passes and as volatility shifts — the rate of that change is gamma.

So the hedge decays. A position hedged perfectly this morning is mis-hedged by the afternoon, and the maker must adjust: buying more shares as the stock falls, selling some as it rises. This continues for the life of every contract on their book, across thousands of positions, mostly automated.

Two consequences follow that matter to a seller.

Hedging is expensive. Every adjustment crosses a spread and pays a commission. In a volatile market, adjustments are frequent and the cost rises sharply. This is a direct input into how widely they quote.

Hedging flow is real trading. Makers buying shares as prices fall and selling as they rise is, in aggregate, a stabilising force in ordinary conditions. It is a genuine market force rather than a bookkeeping detail.

What this explains

Why spreads vary so much between similar contracts. The spread is priced from the maker's hedging cost and inventory risk, not from anything about the contract's merit. A thinly traded strike is hard to hedge cheaply, so it quotes wide. A busy one is easy, so it quotes tight. This is why the bid-ask spread tracks open interest so closely.

Why spreads widen before earnings. Uncertainty about the coming move makes hedging riskier and less reliable. The maker widens the quote to compensate. Nothing about your contract changed; their cost of doing business did.

Why liquidity disappears in a crisis. Market makers are not obliged to quote tightly, and when hedging becomes expensive and unpredictable they widen dramatically or step back. The liquidity you measured on a calm day is not a property of the contract — it is a service being provided at a price, and the price rises exactly when you most want to use it.

Why your fill is often better than the bid. Makers compete, and a resting limit order between the bid and mid is frequently filled because taking your order at a slightly better price still leaves them a spread worth capturing.

What it does not mean

Three conclusions people draw from this that do not follow.

It does not mean the market maker is against you. They are indifferent to your outcome. They hedged the exposure away. Whether your put expires worthless or is assigned makes no difference to a properly hedged book.

It does not mean options are a zero-sum trade against a smarter opponent. The maker is not forecasting. The genuine risk transfer in the options market runs between hedgers who want protection and sellers willing to provide it — who buys put options covers that side. The maker sits in the middle, taking a fee for connecting the two.

It does not mean hedging flow is predictable enough to trade around. There is a cottage industry claiming to infer market-maker positioning and forecast price movement from it. The underlying mechanism is real; the inference from public data to reliable prediction is not, and treating it as actionable is a considerably stronger claim than the mechanism supports.

The useful conclusion

Your counterparty is a service provider, not an opponent, and the service has a price that varies.

That reframes several practical decisions. Contracts with deep open interest are cheaper to trade because they are cheaper to hedge. Wide spreads are information about hedging difficulty rather than about opportunity. And the assumption that you can exit a position at a reasonable price whenever you choose is an assumption about someone else's willingness to quote — reliable most of the time, and least reliable in precisely the conditions that would make you want to.

Which is one more argument for entering positions you are content to hold to expiration. A hold-to-expiry contract needs the market maker once. A contract you intend to manage needs them twice, and the second time is not of your choosing.

How StratosIQ accounts for it

Liquidity is treated as a publication requirement rather than a scoring input. Contracts must clear a minimum open interest and sit inside a spread ceiling before they are scored at all — which is, in effect, a requirement that market makers are willing to quote the contract properly.

Framing it as a gate rather than a weighted factor matters. As a factor, a thin contract with an exceptional premium could score onto the page; as a gate, it cannot. The cost is a shorter list each morning, and the contracts excluded are the ones where the maker has signalled, through the spread, that they would rather not.

Every contract is also scored on a hold-to-expiry basis, which is the assumption under which the spread is paid once.

The full published record, contract by contract and including every loss, is on the performance page.

Worth reading next

Who buys put options covers the end buyers whose demand the maker is intermediating. The bid-ask spread covers what their service costs you per contract.