On Wednesday 11 Jun 2025 a Nifty lot was 75 units, the index closed at 25,141.40 and the weekly option expired the next day, a Thursday. On Wednesday 10 Jun 2026 the lot was 65, the index closed at 23,214.95 and the weekly expired on a Tuesday. Same index, same week of June, a different contract. A lot of what is written about the Nifty lot size or the expiry day was true once and is wrong now. I look for the date on a contract spec before I trust a single number in it. This lesson reads the spec sheet as it stands on 16 Oct 2026, says what changed and why, and shows where to check it.
3By the end you can
- Read a contract spec: lot, expiry day, strikes, tick and settlement.
- Work out the value of a lot and check it against SEBI's band.
- Say why Nifty expires on Tuesday, Sensex on Thursday, and why Bank Nifty has no weekly.
The idea, plainly
A contract spec is the fixed menu of a contract: what it tracks, how many units it holds, when it ends, which strikes exist, how it settles. A trader chooses none of it. SEBI sets the framework and the exchange fills in the numbers by circular. A new rule usually reaches new contracts first, so a screenshot from 2025 can be wrong in three places at once.
Why did the Nifty lot change?
The lot is the number of units in one contract, and the value of a contract is the lot times the index. SEBI's rule, in force for contracts introduced from 20 Nov 2024, fixes the lot so that its value on the day of review sits between 15 lakh and 20 lakh rupees, as a multiple of 5 units and never below 10. Exchanges review it every six months on the average close of the index over the last month, with at least two weeks' notice. A higher lot applies to new contracts only.
The lot is reset by a six monthly review, and old contracts run out on the old lot
Read one more paragraph, 96 words
Under that rule the Nifty lot went from 25 to 75 for contracts introduced from 20 Nov 2024. NSE's circular of 3 Oct 2025 took it from 75 to 65, from the end of day on 28 Oct 2025, using the September 2025 average close. Weekly and monthly contracts already listed kept the old lot until the 30 Dec 2025 expiry. The first expiries on the new lot were 6 Jan 2026 for the weekly and 27 Jan 2026 for the monthly. NSE's circulars name the rule and the month of closes, not the sum.
What are SEBI's rules on lot size, weekly expiry and upfront premium?
Most come from one SEBI circular, of 1 Oct 2024, which made the six changes below. Two shape the contract itself: a bigger minimum value and one weekly index per exchange. A later circular, of 26 May 2025, fixed the expiry days. The rest are about margin, which module F05 takes up. Learn module 11.4 covers SEBI's wider rulebook.
| Measure of 1 Oct 2024 | In force from |
|---|---|
| Option premium collected up front from the buyer | 1 Feb 2025 |
| No calendar spread relief on expiry day | 1 Feb 2025 |
| Position limits watched during the day | 1 Apr 2025 |
| Contract value at least 15 lakh, lot reviewed inside a band | 20 Nov 2024 |
| Weekly expiry on one benchmark index per exchange | 20 Nov 2024 |
| Extra 2% extreme loss margin on short options on their expiry day | 20 Nov 2024 |
Why Tuesday for Nifty, Thursday for Sensex, and no Bank Nifty weekly?
SEBI's circular of 26 May 2025 limited every exchange's expiries to Tuesday or Thursday. Its stated reason: spacing expiry days through the week reduces concentration risk, while too many of them could revive expiry day hyperactivity. NSE proposed Tuesday and BSE proposed Thursday, and SEBI agreed in June 2025. The new days apply to contracts expiring on or after 1 Sep 2025. Before that NSE used Thursday and BSE used Tuesday. Monthly contracts expire on the last Tuesday on NSE and the last Thursday on BSE, and a holiday moves the expiry to the previous trading day.
The term this section turns on: Expiry day
Read one more paragraph, 56 words
The missing Bank Nifty weekly comes from the earlier circular. From 20 Nov 2024 each exchange may list weekly options on one benchmark index only. NSE kept Nifty, and its last weekly expiries on Bank Nifty, Midcap Select and Financial Services fell on 13 Nov, 18 Nov and 19 Nov 2024. BSE's one weekly is Sensex.
Strikes, ticks and settlement
Near the money the Nifty strikes on the dated chain below sit 50 points apart. On the June monthly chain of the same day the far strikes sit wider apart. The tick, the smallest step in an option price, is five paise. Index contracts settle in cash against the index and nothing is delivered. For expiries before 7 Dec 2026 the settlement level is the index close on expiry day. SEBI's circular of 15 Oct 2026 changes that from 7 Dec 2026: the level becomes the index value worked out from the volume weighted average price of its shares over the last 30 minutes of continuous trading, and expiring index contracts stop trading at 3:30 pm on expiry day.
Worked example: the same week, a year apart
Take the two dated chains from the story and do the sum SEBI's rule asks for: index close times lot.
| 11 Jun 2025 | 10 Jun 2026 | |
|---|---|---|
| Nifty 50 close | 25,141.40 | 23,214.95 |
| Lot, units | 75 | 65 |
| Value of one lot, Rs | 18.86 lakh | 15.09 lakh |
| Weekly option expiry | Thu 12 Jun 2025 | Tue 16 Jun 2026 |
Strikes sit 50 points apart near the money and prices move in small ticks
| Calls | Strike | Puts |
|---|---|---|
| Settle | Settle | |
| 277.80 | 23,050 | 99.40 |
| 246.10 | 23,100 | 116.95 |
| 215.75 | 23,150 | 136.70 |
| 188.00 | 23,200 | 158.80 |
| Spot 23,214.95 | ||
| 163.60 | 23,250ATM | 182.45 |
| 139.75 | 23,300 | 209.15 |
| 118.95 | 23,350 | 238.35 |
| 100.20 | 23,400 | 269.15 |
| 83.85 | 23,450 | 303.30 |
Shaded cells are in the money. Prices are settlement prices in rupees per unit.
| Contract and its expiry days | Lot |
|---|---|
| NIFTY on NSE. Weekly on Tuesday. Monthly on the last Tuesday. | 65 |
| BANKNIFTY on NSE. Monthly on the last Tuesday. No weekly since 20 Nov 2024. | 30 |
| FINNIFTY on NSE. Monthly on the last Tuesday. No weekly since 20 Nov 2024. | 60 |
| MIDCPNIFTY on NSE. Monthly on the last Tuesday. No weekly since 20 Nov 2024. | 120 |
| NIFTYNXT50 on NSE. Monthly on the last Tuesday. | 25 |
| SENSEX on BSE. Weekly on Thursday. Monthly on the last Thursday. | 20 |
Five dated changes reshaped the Nifty contract in just over two years
- Bigger lots, one weekly index
Nifty lot goes from 25 to 75 for new contracts. On NSE only Nifty keeps a weekly option.
- Premium paid up front
Option buyers pay the premium up front. No calendar spread relief on expiry day.
- Tuesday and Thursday expiries
NSE contracts expire on Tuesday and BSE contracts on Thursday, for expiries from this date.
- Nifty lot becomes 65
Effective at the end of the day. The first weekly on the new lot expired on 6 Jan 2026.
- Settlement method changes
Expiry settlement uses the last 30 minutes of trading, and expiring index contracts stop at 3:30 pm. SEBI circular of 15 Oct 2026.
Read 2 more paragraphs, 209 words
Both lots sit inside SEBI's band, which is what the rule asks on a review day. The index was 7.7% lower on the second date, and the lot value fell with it, from Rs 18.86 lakh to Rs 15.09 lakh. At 65 units a lot stays inside the band while the index is between 23,077 and 30,769. The close of 23,214.95 was only 0.6% above the lower edge. A review that finds the average close below that edge calls for a higher lot, and a higher lot reaches new contracts only, so two lot sizes can trade side by side for weeks.
The ladder shows the strikes around the at the money strike of 23,250 on the 16 Jun 2026 weekly, found from the parity forward because a weekly has no future. Strikes are 50 points apart and every price moves in ticks of five paise. The table below is the spec sheet for the Nifty, the four other NSE indices with monthly contracts and the Sensex, as the NSE lot file and the exchanges' notices read on 16 Oct 2026. NSE also lists the Nifty India FPI 150, under a circular of 16 Jul 2026, and BSE also lists monthly Bankex and Sensex 50 contracts.
The common mistake
The belief: The Nifty lot is 75 and the weekly expires on Thursday.
It was true on 11 Jun 2025 and wrong a year later, and it is still the first thing that comes up in old videos and screenshots. Contracts already listed keep their old terms until they expire, so even a correct page can describe a contract that has gone. What to do instead: read the date on the page, then check the NSE lot file and the contract specification page, and for a rule read the circular itself. Treat any lot size or expiry day without a date as a question, not a fact.
Key takeaways
- A lot is units per contract. Contract value is the lot times the index.
- SEBI keeps a lot's value inside a fixed band at every six monthly review.
- NSE contracts expire on Tuesday and BSE contracts on Thursday, from 1 Sep 2025.
- Each exchange may list weekly options on one benchmark index only.
- Index contracts settle in cash, and the settlement method changes from 7 Dec 2026.
- Check the date on any lot size or expiry day you read.
Before you trade. Derivatives trading carries a high risk of loss. SEBI's study "Profitability of Individual Traders in the Equity Derivatives Segment (FY25 to FY26)" (August 2026) found that 87.7% of individual traders in equity F&O made net losses in FY26, with aggregate net losses of Rs 91,685 crore. Read the SEBI study