Rollover

The intuition

A futures position has a hard end date. If a trader wants to stay long past the last Tuesday, there is no choice but to sell the expiring contract and buy the next one. The exchange does not do this automatically; the trader does, and the market can see them do it. Over expiry week, open interest drains out of the near month and fills up the next month, and the proportion that makes the move is the rollover. It is one of the few places where the whole market’s intention is visible as a single number: how much of the existing positioning intends to continue.

The number alone is not enough. Shorts and longs both roll, and the percentage does not say which. The spread at which they roll does: when longs dominate the roll they bid up the next month and the calendar spread widens; when shorts dominate it narrows or turns to a discount. Rollover percentage plus spread plus the trend over the month is the reading.

Formula

Rollover % = next-month open interest ÷ (near-month open interest + next-month open interest), measured at the close of expiry day

Rollover cost (points) = next-month futures price − near-month futures price, the calendar spread; annualised = spread ÷ spot × 365 ÷ days between expiries

For options there is no single rollover figure; traders roll a strike forward by closing it and opening a later expiry at the same or an adjusted strike.

Worked example (illustrative numbers)

Suppose it is the last Tuesday of the month. At the close, near-month Nifty futures have 33 lakh units of open interest left and the next month has 1.20 crore units. Rollover is 1.20 ÷ (1.20 + 0.33) = 78%. Spot is 24,000; the near month settled at 24,000 and the next month closed at 24,110, a spread of 110 points against a fair carry of about 98 for the 28 days between expiries.

Reading	This month	Three-month average	Interpretation
Rollover %	78%	72%	more positions carried forward than usual
Spread (points)	+110	+95	longs paying above fair carry to roll
Next-month OI change through the week	rising		fresh positions, not only rolls

For a trader rolling one long lot (65 units), the cost is 110 × 65 = ₹7,150, about ₹780 above fair value. That is a small toll for an individual, but across 1.2 crore units it is the market paying roughly ₹14 crore above fair carry to stay long. The combination of above-average rollover and an above-fair spread is the signature of a crowded, confident long book; the opposite, low rollover at a thin spread, shows positions being abandoned.

Why it matters to an options trader

• It reads conviction behind the futures book. Options positioning on the next expiry is built around a futures level the rollover has just confirmed or abandoned.
• Rolled option positions reshape the chain. Writers rolling a defended strike forward move the put and call walls to the new expiry; reading the next-month chain in expiry week shows where they went.
• The spread is your calendar cost. A long option position rolled to the next month pays the forward difference as part of the new premium.
• Stock rollovers reflect expiry-week behaviour. Because stock contracts are physically settled, low rollover in a stock often means positions are being closed to avoid delivery rather than any view change.

Common mistakes

• Reading the percentage without the spread. 78% rolled at a discount is a very different market from 78% rolled at a premium.
• Comparing against last month only. Rollover is seasonal and event-driven; a three- or six-month average is the baseline.
• Treating options rollover like futures. Options are not rolled mechanically; much of the near-month OI simply expires.
• Legging the roll. Closing the near month and then buying the next month exposes the trader to the market in between; the spread order avoids it.

Indian-market specifics

• NSE monthly contracts expire on the last Tuesday of the month (previous trading day if a holiday); the next month’s contract becomes the near month on the following session, and a new far-month contract is listed so that three months always trade.
• Expiry-week rollover is usually spread across the final four or five sessions, with the largest share on expiry day itself; NSE’s daily open-interest files show the migration contract by contract.
• Calendar spreads between two months can be entered as a single spread order on NSE, which executes both legs at the quoted difference and is how most institutional rolls are done.
• Stock futures and in-the-money stock options are physically settled, so stock rollover is influenced by participants avoiding delivery; index contracts are cash-settled and roll purely on view and carry.

FAQ

What is a good rollover percentage for Nifty?

Above the recent average, at a healthy spread; there is no universal number.

How is rollover cost calculated?

Next-month price minus near-month price, × lot size.

Does rollover tell me whether the market is long or short?

Only with the spread: longs widen it, shorts narrow it.

Is there rollover in options?

Positions are rolled by hand; there is no single options rollover figure.

Related terms

• Rolling, the option-position version
• Basis, what the roll is priced on
• Contango, why a roll costs carry
• Open Interest, the data the percentage is built from