Posted in My Daily Journal · 21 October 2026
A fallback slot that loses, a timing defect fixed in the live Williams buyer, the expiry-day straddle measured as an addition beside the buyers, the streaks study that says how much each lot needs behind it, and the BankNifty door going dead once weekly expiries went away.
Did the fallback slot — a last-chance trade when nothing else fired — help?
No: 20 trades at −₹790 each. The whole race-versus-priority question from yesterday also turns out to rest on 28 trades, which is another reason it was left alone. More useful was finding a timing defect in the live Williams buyer, which was entering one bar late; fixing it moved the leg from 520 trades at ₹430 per trade to 400 trades at ₹558 — fewer, better trades.
How does the expiry-day straddle look as an addition rather than a replacement?
On paper it makes ₹644–800 per expiry day, and a 30% stop beats a 50% stop (₹626 against ₹71 per day in the Tuesday-expiry era). Added beside the buyers it earns ₹803 per day at profit-to-drawdown 10.5, better than replacing them (₹457) or running buyers only (₹346). It failed the capital test we set, because a short straddle needs roughly ₹1.5–1.7 lakh of margin per lot sitting idle between expiries, so it got an audited plug and 30-day paper gates rather than money.
What does a bad run look like for one lot?
For the door: 870 trades, 44% winners, ₹416 per trade, worst drawdown ₹42,305, worst single trade −₹8,119, longest losing streak 10 trades (−₹14.8k) and deepest streak 8 trades (−₹18.0k). For the Williams buyer: 493 trades at ₹474 per trade, worst drawdown ₹59,936. For the combined book: 1,363 trades at ₹437, net ₹5.96 lakh, worst drawdown ₹46,539, and its worst year, 2023, lost ₹37k. Sitting through the worst historical stretch needed roughly ₹60–75k behind each lot, which is the number to size from, not the average year.
BankNifty lost its weekly expiries. Does the door still work there?
Repriced for the monthly era, the any-gap BankNifty door falls from ₹252 per trade to −₹72 — dead. The ≥0.5% gap version falls from ₹728 to ₹153 with profit-to-drawdown 0.77, and the Williams buyer from ₹440 to ₹214. With a month of time value in the premium there is no honest intraday BankNifty buying edge left.
What about holding BankNifty overnight — buy today, sell tomorrow?
It measures at ₹670 a night, profit-to-drawdown 8.2, 11 of 12 years positive, once the data is read correctly under the closing-auction regime, where the 15:29 bar is the post-auction close. But 2015–19 was flat at ₹40 a night and all the profit is 2020 onwards at about ₹1,100, the worst night was −₹46,060, and honestly backing one lot overnight needs about ₹4 lakh. A result that depends on one regime and needs that much capital per lot is a note, not a trade.