Call Writing vs Put Writing: What Option Sellers Do

An option writer is the person on the other side of every option a trader buys: they take in the premium today and carry the obligation that comes with it. On the Nifty and Bank Nifty chain, the strikes where this writing piles up become the "walls" everyone watches. This post explains what call writers and put writers are actually doing, why their behaviour differs, and how reliably those walls held in our own scored data.

What "writing" an option really means

To write an option is to create and sell it to a buyer, collecting the premium upfront. In return the writer accepts an obligation: a call writer may have to deliver at the strike, a put writer may have to take delivery at the strike. The buyer has a right; the writer has a duty and a fixed reward — the premium.

That asymmetry shapes everything a writer does. Their best case is that the option expires worthless and they keep the full premium, so writers are, by design, positioned against a large move past their strike. They are not predicting where price will go; they are taking a view on where it probably will not go, and getting paid for the time and uncertainty in between.

Call writing: what the seller is really doing

A call writer collects premium for accepting the obligation to deliver at a higher strike. They profit if the index stays below that strike through expiry, so heavy call writing clusters at strikes the writers expect price to struggle to cross.

That is why the strike above spot with the heaviest call open interest is nicknamed the call wall: it marks where writers have concentrated, and it can act as resistance because those writers have an incentive to defend it. But "incentive to defend" is not "able to defend" — on a strong trending day the same writers may be forced to hedge upward, and the wall gives way.

Put writing: what the seller is really doing

A put writer is the mirror image. They collect premium for accepting the obligation to take delivery at a lower strike, and they profit if the index stays above it. Heavy put writing below spot forms the put wall, the strike often read as support.

Put writing carries a particular character on Indian indices: a lot of it is income-style writing in a market with a long-run upward drift, which is part of why put walls behave a little differently from call walls. It is still positioning, not prophecy — a sharp fall can blow through a put wall just as a rally can break a call wall.

How writing shows up on the option chain

Read together, call writing and put writing draw a rough map of where sellers think the session’s edges are:

• Call wall — the strike above spot with the heaviest call writing. Read as potential resistance.
• Put wall — the strike below spot with the heaviest put writing. Read as potential support.
• The band between them is where the most premium has been written, and where writers would prefer price to stay.

These are descriptions of crowd positioning, not signals to act. The writer on the other side of an index option is often hedging an exposure elsewhere, so the same wall can mean very different things. Treat it as context for what sellers are doing, then form your own view.

What our own data says about writing walls

We compute the call and put walls from the morning option-chain snapshot and then score, every session, whether price actually respected them — keeping the misses in. Across more than 600 scored instrument-sessions over the 14 instruments we track, here is how the writing walls held up for the two big indices:

Nifty 50

• Put wall held when touched: 69% (n=16)
• Call wall held when touched: 69% (n=13)

Bank Nifty

• Put wall held when touched: 67% (n=9)
• Call wall held when touched: 29% (n=7)

Two things stand out. First, put walls held around two-thirds of the time they were actually reached on both indices — useful context, though the samples are small because clean touches are rare. Second, the call side split sharply: Nifty’s call wall held about seven times in ten, while Bank Nifty’s held only about three in ten — on a tiny sample of seven touches. Heavy call writing in Bank Nifty did not reliably cap price in our window.

Heavy writing marks a strike a lot of sellers care about — it does not guarantee the strike holds. A Bank Nifty call wall that held only about 3 in 10 times it was touched (n=7) is a small, noisy sample. Read every wall with its sample size attached, and decide for yourself. We publish the weak numbers on purpose.

The full, continuously updated table — hits and misses, with sample sizes — is free and login-free on our public Scoreboard. For the deeper write-up of how often these walls actually hold, see do option walls actually hold in Nifty and Bank Nifty.

What option writing does not tell you

Writing concentration is a snapshot of positioning, not a forecast. It cannot tell you why a writer is there — income, a hedge, or one leg of a spread all look identical in the open-interest column. It says nothing about the premium they took in or the level at which they will give up and hedge. And because every written contract has a buyer on the other side, the wall never tells you which side is "right." Used as one layer of context alongside price and your own plan, the writing map is informative. Used as a prediction, it disappoints.

TrueTrend turns market structure like this into a clear, at-a-glance read across Nifty, Bank Nifty and the major F&O names — create a free account and see it live.