This is a fascinating question that gets to the heart of options pricing and arbitrage. Let me clarify the mechanics before addressing why the scenario you describe would not persist in a real market.

The Setup You're Describing

• NIFTY is currently at some level (call it S for spot)
• A European put with strike K has intrinsic value = K - S = 2,400 (meaning NIFTY is well below the strike)
• The put is trading at 1,600, which is below intrinsic value of 2,400

Why This Arbitrage Wouldn't Exist

If a European put were genuinely trading below intrinsic value, it would create a risk-free arbitrage. Here's how an arbitrageur would lock in the profit:

1. Buy the underpriced put at 1,600
2. Buy NIFTY at the spot price (using borrowed funds)
3. At expiry, exercise the put to sell at the strike, receiving K - S = 2,400
4. Repay the loan used to buy NIFTY
5. Pocket the risk-free profit of 800 (2,400 - 1,600), minus small interest costs

Everyone would do this until the put price gets bid up to at least intrinsic value plus carry costs.

Why It Might Appear Undervalued

What you're likely observing is one of these scenarios:

The Real Answer

If a put were truly available below intrinsic value with no catch — no one should just buy NIFTY. They should buy the put (plus the underlying) and earn risk-free profit. But that's precisely why the market won't let that price stand. Arbitrageurs exploiting this trade push the put price back up to fair value almost instantly.

The scenario you describe is the options equivalent of finding a ₹2,000 note selling for ₹1,600. If it were real, the trade would already be gone by the time you saw it.

Exactly right — and this is the key insight. Let me formalize it.

The Put-Call Parity / Cost-of-Carry Framework

For a European put, the no-arbitrage lower bound is not simply intrinsic value (K - S). It's the present value of the intrinsic:

Put ≥ PV(K) - S + PV(expected dividends)

What this means in your case:

• Strike (K) minus Spot (S) = 2,400 intrinsic at expiry
• But you don't get that 2,400 today — you get it in 1.5 years
• The present value of 2,400 discounted at the risk-free rate (~6.5-7% in India) is roughly 2,170-2,180
• So the theoretical minimum for the put is about 2,170, not 2,400

But your put is at 1,600 — still below that. So what explains the gap?

The Missing Piece: Funding the Hedge

Here's the critical point you've already identified:

To arbitrage this, you must: 1. Buy NIFTY — but you don't get a stock basket for free 2. You either borrow cash and pay interest, or use your own capital and lose what it could earn elsewhere

The cost of buying NIFTY for 1.5 years at ~7% interest is approximately: - If NIFTY is around, say, 22,000 → interest cost over 1.5 years ≈ 2,300-2,400

So the full picture:

The put at 1,600 is not mispriced — it is correctly priced once you account for the cost of carry on the underlying.

Why Everyone Shouldn't Just Buy the Put

Because buying the put alone is not a free lunch. If you:

• Only buy the put: You pay 1,600 now, NIFTY could rally, and the put expires worthless. That's a directional bearish bet, not arbitrage.
• Put + underlying (conversion): The arbitrage requires buying NIFTY too. Once you factor in funding costs for 1.5 years, the edge vanishes. The market has already priced the put so that the risk-free return equals the risk-free rate.

The Deeper Point

This is the market doing exactly what it should. The put discount of 800 (2,400 - 1,600) is not free money — it is precisely the time value of money on the capital required to hold NIFTY for 18 months. The put seller is effectively charging you the interest you'd otherwise earn on your cash, which is why the put looks "cheap" relative to raw intrinsic.

The market isn't stupid — it's discounting.

Ah, now I see what you're getting at — and this is a genuinely clever observation. Let me re-frame it properly.

The Trade

• Buy the European put at 1,600
• Intrinsic at expiry = 2,400 (K - S, with NIFTY where it is today)

You're not hedging an existing position. You're asking: why not buy this put as a standalone instrument?

The Payoff at Expiry (1.5 Years)

Let's say NIFTY spot today = S₀, Strike = K, so K - S₀ = 2,400.

The Problem: This Is Not a Hedge — It's a Directional Bet

You said the put "ensures ~2.5% return no matter how much NIFTY falls." But the return is not independent of NIFTY's movement relative to where it is today:

• If NIFTY rallies, you lose. Potentially everything.
• If NIFTY stays where it is, you make 800.
• If NIFTY falls from here, you make 800 + the incremental intrinsic.

The put only "ensures" a positive return conditional on NIFTY not rising. That condition is doing all the work.

The 2.5% Framing

If you're thinking of it as: "I'll buy the put, and even if markets do nothing for 1.5 years, I make 800 on 1,600 = 50% return (~33% annualized)" — that's a valid observation, but it's not a risk-free 2.5%. It's a bet that NIFTY won't rally meaningfully.

Why Everyone Doesn't Do This

Because the trade is implicitly short NIFTY at a very specific level. If NIFTY is at 22,000 today and your strike is 24,400 (so intrinsic = 2,400):

• NIFTY rising to 25,000 means your put expires worthless — you lose 1,600
• That's a ~14% rally over 1.5 years — entirely plausible
• The market-implied probability of that happening is embedded in the 1,600 price

You're not being compensated for nothing. You're being compensated for bearing the risk that NIFTY rallies, which in a bull market is a very real risk. The discount from 2,400 to 1,600 reflects the market's collective view of that probability.

The TL;DR

What looks like a cheap put with guaranteed return is actually: you are selling a NIFTY call synthetically. The put + the time value implies you're short the upside. That's the risk you're taking, and that's why everyone isn't piling in.

Ah — now I understand. You're asking a much sharper question.

The Question, Restated

You hold a long NIFTY position. You can buy a 1.5-year European put for 1,600 that guarantees you can sell at a level 2,400 above current spot. So:

• You pay 1,600 now
• In 1.5 years, no matter what happens, you are guaranteed at least 2,400 more than today's NIFTY value
• Net minimum gain: 2,400 - 1,600 = 800 over 1.5 years
• That's a floor return of ~2.5% annualized, risk-free, with unlimited upside

Why That's Wrong — And Why It Feels Right

If the above were true, you'd be correct: everyone should do it. But there's a subtle misalignment.

The put's intrinsic value of 2,400 is K - S₀, calculated at today's spot. That is the payoff if expiry were today. At expiry in 1.5 years:

• The put pays max(K - S_T, 0)
• The NIFTY position is worth S_T
• Combined: K (the strike), if ST < K, or ST if above

So your hedged portfolio is worth max(K, S_T) at expiry. You paid S₀ + 1,600 for it.

The net minimum at expiry is K - (S₀ + 1,600).

But K - S₀ = 2,400, so:

K - (S₀ + 1,600) = 2,400 - 1,600 = 800

That does appear to be a guaranteed 800. And if NIFTY rallies, you capture the upside too.

So Is It Really a Free Lunch?

No — and here's the catch. The 2,400 intrinsic value is not 2,400 of free money. It's 2,400 of embedded funding cost relief.

Remember why the put is at 1,600 not 2,400: because the market is discounting. The 800 difference is the interest you could have earned on the 2,400 over 1.5 years. When you buy the put at 1,600 and hold NIFTY:

• You've tied up capital in NIFTY for 1.5 years
• The "guaranteed 800" is simply the market returning to you the time value of money on that tied-up capital
• If you instead sold NIFTY and put the cash in a 7% FD for 1.5 years, you'd earn roughly the same 800 (on the 2,400-equivalent capital)

The put isn't cheap. It's fairly priced. The 800 "guaranteed return" is just the risk-free rate in disguise.

The Real Comparison

The put-hedged strategy gives you equity upside with a floor — but the floor is just recovering the time value of your own money. It's not a bargain. It's the mathematically fair price of insurance.

The Bottom Line

You're not wrong that it's a great portfolio structure — protective put + long underlying is a legitimate strategy. But the put isn't "too cheap to ignore." It's priced exactly where put-call parity says it should be for a 1.5-year option. The apparent bargain vanishes once you account for what that same capital could earn elsewhere, risk-free.

Now that is the right question.

The Core Insight

You've put your finger on something real: European options should trade cheaper than otherwise-identical American options, and that discount is a genuine advantage if you know you won't need early exercise.

The American put premium over European is the value of the right to exercise early — which matters most when:

• The underlying pays dividends (early exercise before ex-div)
• Deep in-the-money with high interest rates (pull intrinsic early)
• There's a borrow cost on the underlying

India vs US: The Structural Difference

For a genuine long-term hedger who will hold until expiry, the European put is the more efficient instrument. You are not paying for a feature (early exercise) you will never use.

Why This Matters In Practice

With NIFTY at ~7% rates and SPY at ~4% rates, the early-exercise premium on an American put is real. At 1.5 years out, deep ITM, that premium can be meaningful — maybe 10-15% of the option price. For a long-only investor who:

• Plans to hold the index for 1.5 years
• Wants a floor, not trading flexibility
• Doesn't need to monetize the put early

...the European structure delivers the same protection at lower cost. That saving compounds over repeated hedging cycles.

The Caveat

The comparison isn't entirely apples-to-apples:

• Liquidity: SPY options are the most liquid options market in the world. NIFTY long-dated options, while decent, are thinner at the far end. The bid-ask spread may eat some of the theoretical saving.
• Currency: If you're an INR-based investor, hedging NIFTY avoids FX risk. Hedging SPY introduces it.
• Tax: Indian options taxation vs US — different treatment of gains. This can swamp the structural advantage.

The Bottom Line

Yes — for a buy-and-hold index investor who wants downside protection over a known horizon, European puts on NIFTY are structurally cheaper insurance than American puts on SPY, precisely because you are not paying for the early-exercise option you will never use. It's not a free lunch, but it is a more efficient contract design for that specific use case.

Let me pull up the actual numbers. I'll look at NIFTY and SPY current levels, then find comparable deep ITM puts about 1.5 years out.Only SPY loaded — let me try NIFTY separately, and also search for the NIFTY level.NIFTY isn't in the local database, so I'll use the numbers you provided. Now let me get the SPY option chain.No options data available in the local DB. Let me work with what we have and source the SPY numbers from the web.Let me get cleaner data for the Jan 2028 puts, especially the deep ITM ones.I now have clean data from the option chain. Let me extract the key numbers and build the comparison. From the data:

SPY: Last price $757.57 (Aug 3, 2026)

Now let me pick a comparable deep ITM put. I need ~10-11% ITM (matching your NIFTY scenario where intrinsic is ~11% of spot). For SPY at ~758, a strike of ~840 would give intrinsic ~$82, or about 10.8% of spot.

From the chain, the Jan 21, 2028 SPY 840 Put: last price $97.64 (bid-ask roughly 97-98), strike 840, expiry Jan 21, 2028 (~17 months).

Let me now construct the full comparison using your NIFTY numbers.

NIFTY vs SPY — Deep ITM Put Hedge Cost Comparison

Parameters matched: ~1.5 years expiry, ~11% ITM, European (NIFTY) vs American (SPY)

*The SPY 840 put has positive time value — it trades above intrinsic because it's American and not deep enough ITM. The market prices in early-exercise optionality.

Let me grab a deeper ITM SPY put where the discount is actually visible. Looking at the chain for the SPY 900 Put: last $159.55, intrinsic = 900 - 757.57 = $142.43.

Let me compute a proper comparison with the 900 strike.

Final Comparison Table

What This Shows

Your NIFTY put is structurally cheaper in two ways:

1. Negative time value: The NIFTY put trades 800 below intrinsic — meaning the seller is paying you to hold it. The SPY put (with earlier exercise rights) always carries positive time value at these strikes because the American feature has real economic value in a high-rate environment.

2. European discount is real: Even if you match the exact same % ITM, the SPY American put will trade at a premium because you're paying for the right to monetise deep intrinsic early when rates are high. With NIFTY at 7% rates, the theoretical early-exercise premium on an American put would be meaningful — but by using a European contract, you avoid paying for it entirely.

Bottom line: For a buy-and-hold index investor who will carry the position to expiry, the NIFTY European put is genuinely cheaper insurance. You are not paying for early-exercise optionality you will never use, and at ~4.9% annualised hedge cost vs India's ~7% risk-free rate, it's effectively being offered at a discount to fair carry. That discount is the "European dividend" — and it's structural, not a market inefficiency.