Put Ratio Spread

Quick answer: A Put Ratio Spread buys one put and sells two lower-strike puts of the same expiry, usually for a net credit; because it is net short one put, the worst case is a large but finite loss if the underlying collapses toward zero.

In simple words

You buy one put and sell two lower puts, usually taking in a small credit. If the market drifts down to the lower strike you do well, because the put you own gains while the two you sold have not yet turned against you. Below that strike the extra sold put has no cover, and your loss grows as the market keeps falling. The loss is not literally infinite — the market can only fall to zero — but the worst case is enormous. This is a bet on a mild fall that stalls, and it hides a large open-ended-feeling risk if the decline runs on.

Payoff diagram

Professional explanation

Undefined-risk, but finite at the bottom

The position holds one long put and two short puts of a lower strike. Above the short strike the long put and one short put broadly offset. Below the short strike, only one of the two short puts is covered by the long put — the second is naked. A naked short put loses as the underlying falls, but unlike a naked call it does not lose without limit: the underlying can fall only to zero. So the risk is undefined in the schema sense — nothing in the structure caps it, only the underlying running out of room — yet the worst case is a large finite number, not the unlimited loss of a call ratio spread. Write it as a loss all the way to zero, never as unlimited.

The profit tent points down

At expiry the payoff is a tent whose peak sits at the lower short strike, where the long put is fully in the money and both short puts are worthless. From the credit at high prices the profit rises to that peak, then falls as the underlying drops further and the naked put bites, crossing zero at the lower breakeven and deepening toward the worst case near zero. The peak equals the strike width plus the credit. The trade wants the underlying to settle at the short strike; it fears a continued collapse below the lower breakeven.

Not a backspread, and not unlimited

Two confusions to clear at once. First, this is a ratio spread, not a put backspread: it sells two and buys one, so it is net short and undefined-risk, whereas a put backspread buys two and sells one and is net long, defined-risk, and profits from a crash. Second, its worst case is finite. The call ratio spread's tail is genuinely infinite because the underlying can rise without bound; the put ratio spread's tail stops at zero. Both are undefined-risk, but only the call version is truly unlimited — a distinction worth stating precisely.

Margin, assignment and the crash scenario

The uncovered short put attracts naked-option margin, which is high and rises as the underlying falls toward the short strike. On stock options either short put can be assigned early, and below the strike the naked one delivers long stock at the strike with a paper loss and a cash outflow. On cash-settled index options there is no assignment, but a gap-down through the short strike can produce a large settlement loss with no chance to manage it. Because equity crashes are fast and correlated with volatility spikes, the put ratio spread's worst case tends to arrive quickly and all at once.

Construction

1. Buy one higher-strike put of the chosen expiry.
2. Sell two lower-strike puts of the same expiry, typically taking in a net credit.
3. Recognise that one of the two short puts is uncovered, so the downside loss runs toward the underlying reaching zero.

Market outlook

A trader may study a put ratio spread when expecting the underlying to drift down modestly toward a support level and stall, with implied volatility rich enough that the two short puts fund the long one for a credit. The peak sits at the lower short strike. The view is invalidated by a continued fall below the lower breakeven, where the uncovered put produces a large loss toward zero, or by a volatility spike that inflates the short puts. Because equity declines are often fast and volatile, the failure mode can arrive abruptly, so the structure demands a firm floor on how far the underlying can fall and active management.

Risk profile

This is an undefined-risk position: nothing in the structure caps the loss below the short strike, because one of the two short puts is uncovered. The loss deepens all the way down as the underlying falls, stopping only when the underlying reaches zero — a large but finite worst case, not the genuinely infinite loss of a call ratio spread. On the upside the risk is limited to a small loss or the credit. The defining feature is the naked short put and the loss-toward-zero it carries, which is why margin is charged as if on a naked position rather than a hedged spread.

Reward profile

The maximum profit is the strike width plus the net credit, reached only if the underlying settles exactly at the lower short strike at expiry, where the long put is fully valued and both short puts expire worthless. Away from that peak the reward falls off — toward the credit above the long strike and toward a large loss below the lower breakeven. The reward is concentrated at one price and sharply path-dependent, the price of accepting a loss that runs toward zero.

Margin requirement

Because one short put is uncovered, brokers and the exchange charge naked-option margin on the unhedged leg, so the requirement is high and rises as the underlying falls toward the short strike. SPAN plus exposure can increase intraday, particularly during volatility spikes. This is not defined-risk for margin purposes. NSE and brokers revise margin rules periodically, so confirm the current requirement before trading.

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

The position is net-short vega, so rising implied volatility works against it — the two short puts inflate faster than the single long put. This is especially punishing on the downside because equity falls are typically accompanied by sharp volatility spikes, so vega and direction turn hostile together exactly when the naked put is threatened. Falling volatility helps and is part of why the trade is opened when premiums are rich. But favourable volatility does not remove the structural risk: a continued decline below the lower breakeven still produces a large loss toward zero regardless of what volatility does.

Time decay

Time decay works for the position while the underlying stays above the short strike, because more options are sold than bought and net theta is positive. Each quiet day erodes the two short puts in the trader's favour faster than the long put, which is why the tent peaks at expiry. Near expiry, with the underlying close to the short strike, negative gamma is large — small moves swing profit and loss sharply, and a late break below the strike converts a decaying winner into a rapidly deepening loss.

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

• Calling the downside unlimited: it is a large but finite loss toward zero, and describing it as infinite confuses it with the call ratio spread, which genuinely is.
• Believing the credit measures the risk, when a continued fall below the lower breakeven produces a loss many times the premium collected.
• Confusing it with a put backspread: this sells two and buys one, so it is net short and undefined-risk, not the net-long, defined-risk backspread that profits from a crash.
• Ignoring that equity declines are fast and volatile, so the worst case can arrive abruptly on a gap-down with no chance to manage the naked leg.
• Underestimating the naked-option margin, which is high and rises as the underlying falls, potentially forcing an exit at the worst moment.
• On stock options, overlooking early assignment of a short put, which below the strike delivers long stock at the strike with an immediate paper loss and cash outflow.

Advantages & disadvantages

Adjustments & exits

• Buying a further-out put against the naked short converts the position into a defined-risk structure such as a put broken-wing butterfly, at the cost of some credit.
• Rolling the short puts down and out as the underlying falls lowers the danger zone, but adds risk and does not guarantee escaping the tail.
• Closing one of the two short puts removes the uncovered leg, leaving a plain bear put spread with defined risk and a smaller position.
• Taking the whole trade off as the underlying approaches the short strike near expiry avoids the violent gamma and the deepening loss below it.

Adjustment is a decision about risk, not a way to rescue a losing view. See Adjustments and Exit Planning.

Professional usage

Volatility desks use put ratio structures to shade downside exposure and monetise a rich put skew, usually as part of a larger managed book rather than a standalone bet, hedging the uncovered wing with futures or further options as the market moves. The credit and negative vega express a view that the underlying eases toward support and volatility softens, with the tail controlled by size limits. For a retail trader, the fast, correlated nature of equity declines and the rising naked margin make the uncovered leg difficult to manage, so the structure is among the less forgiving to carry through a falling market.

Frequently asked questions

Voice search & related questions

Natural-language questions people ask about the Put Ratio Spread.

Sources & references

• NSE — Derivatives
• SEBI — Investor education
• S. Natenberg, Option Volatility and Pricing

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