Why this isn't the usual 0DTE post
Every 0DTE post on this blog so far has been a version of the same trade: the hedged ratio straddle — buy 1 ATM CE and 1 ATM PE, sell 3 OTM CE and 3 OTM PE against them, and ride the "tent" payoff into the close. Six trades, six wins, ₹25,348 total, and a tail that's never once been tested. That trade leans on one assumption: that the index grinds to its final level through ordinary continuous trading, and that decay near the close behaves the way it has all day.
That assumption stopped being reliable on 3 August 2026, when NSE switched on the Closing Auction Session — a new way of setting the official closing price for index-linked securities. Instead of the close simply being the last traded price (or a short trailing average of it), the exchange now runs a structured auction in the final minutes: eligible orders are collected and matched at a single equilibrium price, the level where the maximum volume can execute. On the very first day this went live, Nifty's official close moved by roughly 200 points relative to where continuous trading had it — not a technical glitch, just what an auction-based match can do when order flow is lopsided in the last few minutes. Since Nifty's closing level feeds directly into how index options settle, this isn't a cash-market curiosity; it changes what "the close" means for anyone holding index options into expiry.
That's the whole reason this post exists. The tent trade is built to be held into the close and profits from a specific decay pattern in the last hour. With a closing mechanism that can now put a discontinuous jump right where I'd normally be riding smooth theta, I didn't want to find out what that trade looks like on a day the auction moves against me. So the tent stayed off, and I traded something else.
What I did instead
I watched, rather than deployed on the open. Nifty's ATM straddle premium was decaying steadily through the morning and into early afternoon — nothing dramatic, just ordinary Tuesday-expiry theta bleed. By 1:00 pm, with no sign of the kind of move that would justify holding a directional view, I sold a strangle well outside the money rather than anywhere near ATM, and planned to be flat well before the new auction window could do anything unexpected to the settlement.
| Leg | Strike | Action | Premium | Lots | Units |
|---|---|---|---|---|---|
| Short call | 24550 CE | Sell | 11.80 | 2 | 130 |
| Short put | 24350 PE | Sell | 8.75 | 2 | 130 |
Nifty lot size is 65, so 2 lots = 130 units.
The math
| Metric | Value |
|---|---|
| Credit, CE | 11.80 × 130 = ₹1,534.00 |
| Credit, PE | 8.75 × 130 = ₹1,137.50 |
| Total credit | ₹2,671.50 |
| Breakevens | 24341.25 – 24561.80 (≈220-point range) |
| Result | +₹2,311 (≈86.5% of total credit) |
Both legs decayed hard through the afternoon — this was late-cycle 0DTE theta doing what it always does, just captured from a distance instead of at the wire. I closed the position with time still on the clock, comfortably ahead of the close and whatever the auction window did with it.
What changed and what didn't
The read didn't change: sell premium on an index that's decaying into a same-day expiry. What changed was where I was willing to sell it (further out, not ATM) and when I was willing to be out (well before the close, not at it). The tent's edge comes specifically from being positioned tight around the pin into the final minutes — that's exactly the window CAS has made less predictable, so I gave it up for this trade and took a smaller, farther-out, earlier-exit version instead. ₹2,311 is a fraction of what a clean tent day pays, and that's the trade-off: less edge, less exposure to a mechanism I don't have a season of data on yet.
What I still don't know
One auction day isn't a sample. I don't yet know how the settlement print behaves on a quiet day versus an imbalanced one, whether the ±3% auction band changes the practical risk of holding into the close, or whether the tent can simply be re-timed — entered the same way but exited a few minutes earlier — rather than abandoned on 0DTE days. That's the next thing to test, on paper first, before the tent goes back on with real premium behind it.
Disclaimer
This is a personal trading journal. It is a record of my own trades, my own money and my own mistakes — nothing more.
Nothing here is a trade recommendation, a tip, a call, or advice of any kind. I am not a registered adviser and I am not qualified to tell anyone what to do with their capital. The strikes, premiums, entries and exits above are what I did, not what you should do.
If you read this blog and place a trade because of it, that trade is yours. I accept no responsibility for anyone else's losses. Do your own research, size for your own risk, and understand that options can lose you more, faster, than you expect.