Cash-Secured Put

Quick answer: Cash-Secured Put is a short put backed by enough cash to buy the underlying at the strike if assigned: you collect a premium for accepting the obligation to buy, and the set-aside cash makes that purchase funded rather than forced.

In simple words

You would be happy to buy something at a lower price than today's. So you promise to buy it at that price for the next month, and you are paid a fee for the promise. You put the full purchase money aside so that if you are held to it, you can simply pay and take delivery. If the price stays high, no one makes you buy and you keep the fee. If it falls below your price, you buy at your price — which you wanted — but you now own something worth less than you paid, cushioned only by the fee.

Payoff diagram

Professional explanation

What makes it cash-secured

The option leg is a plain short put. What makes it cash-secured is entirely off to the side: you set aside the full amount needed to buy the underlying at the strike, and you leave it there. That set-aside is the whole point. It means assignment is a purchase you have pre-funded and pre-agreed to, not an event that catches you short of cash. The premium you collect is your payment for standing ready to buy. Nothing about the cash changes the payoff at expiry — it changes who is in control if the option is exercised.

Why the risk is undefined, not capped by the cash

It is tempting to think the set-aside cash caps the loss. It does not. The cash funds the purchase, but once you own the underlying it can keep falling toward zero, and your loss grows with it. On this site, risk is defined only when the position's own structure caps the loss; a short put has no long leg to do that. So the maximum loss is bounded only by the underlying reaching zero — large and finite, not unlimited, and not made smaller by having the cash ready. The cash secures your ability to pay, not your downside.

The 'getting paid to place a limit order' framing

A popular pitch calls the cash-secured put a way to get paid while waiting to buy at a lower price. There is a grain of truth: if the underlying never falls to your strike, you keep the premium and buy nothing. But the framing hides the asymmetry. If the underlying collapses far below your strike, you are still obliged to buy at the strike — you do not get to buy at the new, lower price. So you are paid a small premium to take on the full downside from the strike to zero. A limit order has no such obligation and no such tail.

Compared with simply holding cash

Against holding cash, a cash-secured put earns a premium but takes on real risk: in a sharp fall you end up owning a depreciated holding, having converted safe cash into a losing position. Against buying the underlying outright today, it is milder — you buy lower, if at all, and you keep a premium. So it sits between cash and a long holding: more reward and more risk than cash, less immediate exposure than an outright purchase. It is a bullish-to-neutral position, not a conservative one.

European settlement changes the assignment story

The classic cash-secured put assumes you can be assigned the underlying and end up owning it. That holds for physically-settled stock options. For NIFTY and Bank Nifty, which are European and cash-settled, there is no delivery: if the put finishes in the money you simply pay the cash difference, you never take possession of an index you cannot own. The economics of the loss are the same, but the 'I wanted to own it anyway' comfort does not apply to a cash-settled index put — you just book the loss in cash.

Construction

1. Decide on an underlying you would be willing to own and a strike below the current price at which you would buy it.
2. Set aside, in cash, the full amount needed to buy one lot at that strike, and leave it untouched.
3. Sell one put at that strike, collecting the premium.
4. Hold to expiry: if the underlying stays above the strike the put expires worthless and you keep the premium; if below, you buy at the strike (or, for a cash-settled index, pay the difference).

Market outlook

A trader may study a cash-secured put when they hold a bullish-to-neutral view on an underlying they would genuinely be content to own, and option premiums are rich enough to reward the wait. The condition that invalidates it is a bearish view: if you expect a meaningful fall, selling a put obliges you to buy into that fall at the strike, which is precisely the wrong side. It also loses its appeal if you would not actually want the underlying at the strike, because then assignment leaves you holding something you never wanted, cushioned only by a small premium.

Risk profile

A cash-secured put carries undefined risk. The set-aside cash secures your ability to pay for the underlying; it does not cap the loss. Once assigned, you own the underlying and it can fall toward zero, so the loss is bounded only by that — the underlying running out of room to fall — and not by the position's own structure. On the illustrative legs the worst case is 23,489 per unit if the underlying went to zero, a large but finite figure. This is why it is undefined risk despite being fully funded: the cash removes the funding problem, not the market problem.

Reward profile

The reward is capped at the premium collected. Whatever happens, you cannot make more than the credit you received when you sold the put; on the illustrative legs that is 211 per unit, or ₹15,825 per lot. If the underlying stays above the strike, the put expires worthless and the premium is your whole gain. There is no participation in the underlying's rise — a put seller does not benefit if the market rallies away, only from the market staying above the strike. It is a small, fixed reward against a large, variable risk.

Margin requirement

In a genuinely cash-secured put the full strike value is set aside in cash, so the position is funded outright rather than run on leverage. A broker may still frame the requirement as SPAN plus exposure margin, but the trader's intent is to hold the entire assignment amount. This is what separates it from a naked put, where only the margin is posted. NSE and brokers revise margin rules periodically; the defining feature here is the cash you choose to hold, not the minimum you are permitted to post.

Greeks exposure

The sign on each Greek above is computed, not asserted: it is the net exposure of the illustrative legs at spot 24,000 with 30 days to expiry, priced with Black–Scholes using each leg's implied volatility calibrated from its own quoted premium. A sign can flip as the underlying moves — the panels below show where. See Methodology.

Volatility impact

A cash-secured put is short one option, so it is short volatility. When implied volatility rises, the put you sold becomes dearer to buy back and the position marks against you even before the underlying moves; a volatility spike, which usually accompanies a falling market, therefore hits you twice. When implied volatility falls, the put cheapens and the position gains. Selling when premiums are rich gives both a larger cushion and a position that profits if that richness later drains. The vega is negative and, near the strike, not trivial — an event-driven volatility jump can turn a quiet position red on its own.

Time decay

Time decay is the engine of the position. The put you sold bleeds time value every day, and that bleed accelerates as expiry nears, so a cash-secured put held into its final weeks earns theta at an increasing rate — provided the underlying stays above the strike. If the underlying sits well above the strike, decay is slow because little time value remains; if it hovers near the strike, decay is fast but so is the risk of assignment. The position sits on the part of the decay curve that pays, but only while the market cooperates.

Practical examples

Lot sizes used above (NIFTY 75, BANKNIFTY 30) are those in force at the time of writing; NSE revises them periodically. Figures exclude brokerage, STT, exchange charges, stamp duty and GST, all of which materially affect small spreads.

Common mistakes

• Selling a put on an underlying you would not actually want to own, so that assignment leaves you holding something you never wanted with only a small premium as consolation.
• Believing the set-aside cash caps the loss — it funds the purchase, but the underlying can keep falling toward zero once you own it.
• Treating it as a way to get paid for a limit order while ignoring that a limit order has no obligation and no downside tail below the strike.
• Selling too close to the price for a fat premium, which raises both the credit and the odds of being assigned into a falling market.
• Ignoring that a volatility spike, common in a sell-off, marks the short put against you even before the underlying reaches your strike.
• Forgetting that on a cash-settled index there is no 'I wanted to own it anyway' outcome — a finishing in-the-money put is simply a cash loss.

Advantages & disadvantages

Professional usage

Institutions do sell puts to acquire holdings at a discount or to harvest the volatility risk premium, and a cash-secured framing — funding the potential purchase in full — is close to how a disciplined allocator would run it. But desks size it across many names and treat the premium as compensation for a known, modelled tail, not as free yield. The retail version concentrates that tail in a single underlying and often understates the capital cost of holding the cash. The concept transfers; the comfort depends on diversification and on genuinely wanting the underlying.

Frequently asked questions

Voice search & related questions

Natural-language questions people ask about the Cash-Secured Put.

Sources & references

• NSE — Equity Derivatives
• McMillan, Options as a Strategic Investment
• SEBI — Investor education

Last reviewed 9 July 2026. Educational content only — not investment advice.