Option Writer
The seller who pockets the premium up front and takes on the obligation — limited reward, large risk, margin required.
Definition
An option writer (or seller) is the party that creates and sells an option contract. In exchange for the premium received from the buyer, the writer takes on the obligation to honour the contract if assigned — to sell the underlying (call writer) or buy it (put writer) at the strike.
Why it matters
Writing flips the risk profile: the writer's reward is capped at the premium, while losses can be large (theoretically unlimited for a naked call). Writers profit from time decay (theta works in their favour) and from options expiring worthless. Because the risk is open-ended, exchanges require writers to post margin as collateral. Writers' positioning shows up as the open interest that builds OI walls on the chain.
Example
You write a 22,800 NIFTY call and collect a premium of 90. If NIFTY stays below 22,800 at expiry, the call expires worthless and you keep the full 90. If NIFTY rallies to 23,000, the call is worth 200 — you face a loss of 110 per unit (200 settlement minus 90 received).
See where writers are positioned
TradePulse's option chain shows live OI buildup and changes that reveal where writers are defending strikes.