The exchange has been watching. It always was. But now, it watches longer.
NSE’s new circular does one simple thing: it extends the memory from one day to five. What used to reset every morning now stays on record for five full days. Every trade, every pair, every contract, the exchange sees it all, and it does not forget quickly anymore.
Here is a simple breakdown of how the new Reversal Trade Cancellation Mechanism (RTCM) works and what it means for you.
1. What is a Reversal Trade?
A reversal trade happens when two people (or one person using two different accounts) make a trade in a specific contract and then “reverse” it shortly after.
- Leg 1: Person A buys 100 units from Person B.
- Leg 2: Person A sells 100 units back to Person B.
These trades do not actually change who owns the shares. They just create fake trading volumes or allow traders to secretly move profits and losses between accounts.
2. How Traders Gamed the System (And How RTCM Catches Them)
Imagine two traders, Raj and Priya. Every day, Raj sells Priya 100 shares of a dead, low-volume option contract. Shortly after, Priya sells them right back. Nothing really changes hands; it is like passing the same ₹500 note back and forth.
Why do they do this? Usually for two reasons:
- Fake Volume: By trading back and forth, they make a dead contract look highly active. Unsuspecting retail traders see this volume, think something big is happening, and jump in to buy.
- Profit Shifting: Let’s say Raj wants to book a fake loss to save on taxes, and Priya (his wife’s account) wants to show a profit. Raj sells the shares to Priya for ₹10. The next day, he buys them back for ₹100. Raj officially loses ₹90 per share, and Priya makes ₹90. On paper, it looks like a normal market loss, but the money just moved from one pocket to another.
The Old Loophole: The trick used to be simple. Do the first trade on Monday. Reverse it on Tuesday. In the past, the exchange only looked at trades one day at a time, so it never connected the dots. It was like robbing a store in two separate trips and hoping no one noticed.
The New 5-Day Rule: But now, the exchange has a longer memory. It watches every pair of traders like Raj and Priya or five whole days. Now, if Raj does the first trade on Monday and waits until Thursday to do the reverse trade, the system catches it. If their new trade tips them over the exchange’s limit, the trade is cancelled instantly. No warning.
It is like a shopkeeper who finally started writing everything down in a notebook and flipping back five pages before trusting anyone.
3. Old vs. New Mechanism
Here is a quick look at exactly what changed with the new rules:
| Feature | Old Mechanism (Intraday) | New Mechanism (5-Day Rolling) |
|---|---|---|
| Monitoring Period | Only trades done on the exact same trading day. | Trades are now checked over a rolling 5-day window (Today + previous 4 days). |
| Detection Scope | Traders could hide by doing Leg 1 on Monday and Leg 2 on Tuesday. | The system remembers trades for 5 days. Leg 2 will get caught even if done 4 days later. |
| Aggregation | Quantities were calculated on a daily basis. | Quantities are added up across the entire 5-day period. |
4. How the 5-Day RTCM Works
The exchange looks for pairs of PANs (Permanent Account Numbers) that are trading with each other. Here is the step-by-step process:
- Identification: The system checks if PAN A and PAN B have traded the exact same contract.
- Aggregation: It looks at all the trades between them for the last 4 trading days plus today.
- Threshold Check: If a new trade between these two PANs crosses a set limit (based on total market volume or the client’s own volume), the trade gets flagged.
- Cancellation: The exchange automatically cancels the specific trade that crossed the limit.
5. Eligible Contracts (Where RTCM is Active)
This rule is not active on highly traded stocks (like Nifty 50) because it is almost impossible to “pair” trades in a busy market. It targets low-volume, illiquid contracts:
- Stock Options: Strikes that are 10% or more away from the current price (Deep OTM).
- Index Options (Monthly): Strikes that are 5% or more away from the current price.
- Index Options (Weekly): All strikes if the expiry is more than 15 days away.
- Strikes 5% or more away if the expiry is within 15 days.
- Cash Segment: A specific list of low-volume stocks shared by the exchange every month.
6. Timings of the Mechanism
The exchange does not run this check for the whole trading day.
- initial Check (10:30 AM): All trades done between 9:15 AM and 10:30 AM are added up and checked at once. If any break the rules, they are cancelled right at 10:30 AM.
- Continuous Check (10:30 AM – 3:00 PM): Trades are checked live. If a trade crosses the limit, it is cancelled right away. (Note: The checks stop at 3:00 PM).
7. Critical Impact on Traders
For an average retail trader, this rule will rarely cause issues unless you trade very illiquid, deep OTM options. However, if a trade is cancelled, you face some risks:
- Execution Risk: If you tried to close a position and the trade gets cancelled, your original position stays open. You might not notice this until the end of the day, leaving you with overnight risk.
- “Trade CXL” Status: If you see this cancelled status on your screen, do not try to do the exact same trade again with the same person. It will just get cancelled again.
Summary
The 5-day RTCM now exists for one reason to keep the market honest. And if you trade honestly, it will never come for you.
This rule was not written for the careful trader who picks strikes and checks order books. It was written for the ones quietly passing positions between accounts, dressing up dead contracts with fake volume, and hoping no one looks too closely. The exchange looked. It always was. Now it just looks further back.
For everyone else, nothing changes.