Introductory Context
"There is no universally correct strike for the protective put. The correct strike is the one that balances these three factors for each investor's specific situation. This topic provides the framework for making this balance explicit, calculable, and repeatable rather than intuitive and inconsistent. "
The Strike Selection Framework - Three Inputs
Input 1 -- Maximum acceptable loss (MAL): the percentage decline in the portfolio that the investor is willing to absorb before insurance coverage begins. This is the 'deductible' of the insurance. MAL = 5 percent: very low deductible -- buys an ATM or near-ATM put. MAL = 10 percent: moderate deductible -- buys approximately a 10 percent OTM put. MAL = 20 percent: catastrophe-only insurance -- buys approximately a 20 percent OTM put. The MAL is determined by the investor's capital situation: near-term capital needs suggest lower MAL (tighter protection). Long-term investment horizon suggests higher MAL (accept more volatility, pay less for insurance).
Input 2 -- Insurance cost tolerance: the maximum percentage of portfolio value the investor is willing to pay per year for the protective put. A 1 percent annual budget means choosing puts that collectively cost Rs 2,500 per Rs 2.5 lakh of monthly premium budget (Rs 2,500 x 12 = Rs 30,000 = 1 percent of Rs 30 lakh portfolio). At VIX 14, a 10 percent OTM Nifty put might cost Rs 45 to Rs 60 per unit monthly. At 2 lots (150 units): Rs 6,750 to Rs 9,000 monthly = Rs 81,000 to Rs 1,08,000 annually = 2.7 to 3.6 percent of a Rs 30 lakh portfolio. If the investor's budget is 1 percent annual, a 10 percent OTM put at VIX 14 exceeds the budget -- they would need to accept a larger deductible (15 to 20 percent OTM).
Input 3 -- Specific downside scenario: the investor may have specific scenarios in mind that define the appropriate strike. 'I need to protect against a pre-election correction that might take Nifty from 24,500 to 22,000 (10 percent decline)' suggests an OTM strike near 22,000. 'I need catastrophe insurance against another 2020-type COVID crash (38 percent decline)' suggests a very far OTM put (15 to 20 percent OTM at minimum).
Strike Selection Grid
MAL 5% (tight protection): Buy ATM or 5% OTM put. Premium Rs 100-150 per unit at VIX 14. High annual cost. Best for near-term capital needs. MAL 8-10% (standard protection): Buy 8-10% OTM put. Premium ~Rs 40-80 per unit at VIX 14. Moderate annual cost (2-4% of portfolio). Best for medium-term holdings. MAL 15% (moderate deductible): Buy 15% OTM put. Premium ~Rs 15-35 per unit at VIX 14. Low annual cost (1-2%). Best for long-term holdings with some short-term event risk. MAL 20%+ (catastrophe only): Buy 20%+ OTM put. Premium Rs 5-15 per unit. Very low annual cost. Best for black-swan protection only.
ATM vs OTM vs Deep OTM - The Three Protection Profiles
ATM Protective Put (strike at current Nifty level, delta approximately -0.50): provides coverage from the first point of Nifty decline. Highest premium -- approximately 0.5 to 1.5 percent of Nifty's current value per monthly expiry. Most appropriate for: (a) investors expecting an imminent correction and wanting maximum protection before it begins, (b) investors who have experienced significant gains and want to fully protect the accumulated value, (c) positions with near-term liquidity needs where any decline is unacceptable.
OTM Protective Put (strike 5 to 10 percent below current Nifty, delta -0.15 to -0.30): provides coverage after the market has declined 5 to 10 percent -- the most practical insurance level for most equity investors. Premium is moderate -- approximately 0.2 to 0.5 percent of portfolio value monthly. Most appropriate for: the standard equity portfolio where some volatility is acceptable but a severe correction (10 percent or more) would cause financial or psychological damage sufficient to affect investment decisions.
Far OTM Protective Put (strike 15 to 25 percent below current Nifty, delta below -0.10): provides catastrophic event coverage at very low cost. A 20 percent OTM put might cost Rs 5 to Rs 20 per unit at VIX 14 -- approximately Rs 750 to Rs 3,000 for 2 lots monthly. Annual cost: Rs 9,000 to Rs 36,000 on a Rs 30 lakh portfolio = 0.03 to 0.12 percent annually. Most appropriate for long-term, high-conviction equity investors who accept significant volatility but want protection against the genuinely catastrophic 30 to 40 percent market crashes (2008, 2020) that can permanently impair portfolios.
Combining Strikes for Layered Protection
More sophisticated protective put structures combine two strike levels to create a cost-efficient layered coverage: buy an OTM put for moderate decline protection AND a far OTM put for catastrophe protection. Example: buy 1 lot of 22,000 PE (approximately 10 percent OTM) at Rs 55 per unit + buy 1 lot of 20,000 PE (approximately 18 percent OTM) at Rs 15 per unit. Total premium: Rs 55 + Rs 15 = Rs 70 per unit equivalent, split across two strikes. This layered structure provides: (a) moderate coverage below 22,000, and (b) enhanced catastrophic coverage below 20,000 at a combined cost lower than doubling up on the 22,000 puts.
Using Sensibull's Payoff Builder to Optimise the Strike
Sensibull's Payoff Builder allows building the combined portfolio plus multiple put strikes simultaneously, displaying the total P&L profile at each Nifty level. For the layered structure above: enter the long equity equivalent, the long 22,000 PE, and the long 20,000 PE as separate legs. The combined payoff curve visually shows where the coverage begins, how the protection curve changes below each strike, and what the total premium cost is. This visual optimisation takes five minutes and ensures the selected strike combination delivers the intended protection profile.
The correct protective put strike is not the cheapest available and not the most protective available. It is the strike where the insurance cost equals the value of the certainty it provides for the specific investor's situation. An insurance policy that costs more than the risk it covers is economically unsound. An insurance policy that covers less than the investor is exposed to leaves meaningful risk unaddressed. The correct strike aligns cost and coverage with the investor's actual risk exposure.
Rolling Down the Strike After a Market Decline Is Usually Wrong
A common error: the market falls 8 percent, the 10 percent OTM put is now only 2 percent OTM, and the investor buys additional puts at the new level to 'refresh' the protection. This rolling-down-the-strike approach buys insurance after the risk has partially materialised (when puts are most expensive from elevated VIX) and locks in additional premium cost on top of the original insurance. The correct response to the market falling 8 percent with a 10 percent OTM put still active: the existing put is providing its designed coverage. The deductible has been substantially absorbed (8 of the 10 percent deductible is gone). Wait for the original put's expiry, assess the new market level, and then establish a new put at the appropriate OTM distance from the new Nifty level.
Establish the Strike When Nifty Is at a Support Level
The most cost-efficient time to establish a protective put is when Nifty is at or near a confirmed technical support level. At support, the probability of an immediate large decline (before the put has any meaningful intrinsic value) is lower -- the market has historically bounced from support. Additionally, VIX may be slightly elevated from the approach to support but not at panic levels. The put purchased at a support-level entry provides immediate coverage if the support fails, at moderate cost because VIX is not at panic peaks. Avoid buying protective puts when Nifty is in the middle of a multi-week advance with no nearby support -- the probability of the put ever providing value is lower and the premium reflects the market's assessment of that lower probability.