Three-month disclosure rule
Also written Index rebalancing disclosure rule
The requirement that a proposed rebalanced commodity index — its new weights and constituents — be publicly disclosed at least three months before the exchange starts publishing the index on those new weights.
In plain language
A commodity index's weights are not meant to change without warning. Traders, index funds and anyone using the index as a benchmark need time to prepare before the weights they are relying on actually shift.
So when an exchange rebalances a commodity index, it cannot simply switch to the new weights overnight. It must tell the market what the new index will look like well in advance.
How it works
Chapter 2, section 2.3, sets the specific lead time: a proposed rebalanced index must be disclosed at least three months before the date the exchange starts publishing the index based on the newly announced weights.
This sits within a wider annual rebalancing framework. Index weights and constituents must ordinarily be reviewed and rebalanced at least once a year — NCDEX and MCX both use the calendar year, January to December, as their rebalancing period. But the three-month disclosure applies whenever a rebalancing actually happens, including in extraordinary situations, such as a ban or suspension of trading in a constituent commodity's futures, which can force a rebalancing outside the normal annual cycle. When an index is rebalanced, only its constituents and their weights change — the index's value is not reset to its base value, but continues from where it was.
A worked example
MCX plans to change the weights of its iCOMDEX Bullion Index for the year starting 1 January 2027, shifting the aluminium, copper, lead and zinc weights inside the metals basket.
Under the three-month disclosure rule, MCX must publish the new proposed weights and constituents no later than 1 October 2026 — three months ahead of the date the index actually starts trading and publishing on the new weights. A trader running an index-tracking strategy sees the announced weights in October and has the full fourth quarter of 2026 to adjust his hedges or holdings before the new weights take effect on 1 January 2027, rather than being surprised on the change-over date itself.
Why NISM asks about it
Chapter 2 (Commodity Indices), section 2.3, point 1, on index construction and maintenance, right where the annual rebalancing requirement is introduced. Expect a recall question on the exact lead time — three months — and on the fact that rebalancing does not reset the index to its base value.
Common exam traps
- Three months is measured to the date the index starts publishing on the new weights, not to the date the decision to rebalance was made.
- Rebalancing does not reset the index to its base value. Only the weights and constituents change; the index level itself continues.
- The annual rebalancing cycle and the extraordinary-situation trigger are two different reasons a rebalancing can happen — but the three-month disclosure applies to both.
Where this is taught
Free preparation for NISM Series XVIRelated terms
- Average Daily Trading VolumeThe liquidity test a commodity future must pass before its price may carry weight in a tradeable commodity index — Rs 75 crore a day for agri, Rs 500 crore for non-agri.
- Composite indexA commodity index spanning several segments — energy, metals, bullion — whose constituents must each weigh 1 to 30 per cent, with at least 80 per cent of the weight in sufficiently liquid futures.
- Sectoral indexA commodity index built from the futures of a single segment — bullion, base metals, energy or the guar family — with fixed annual weights and no 30 per cent cap per constituent.
- Volume-based indexAn index whose weights shift daily with market value, the way equity indices work — unlike commodity indices, which fix weights for a year at a time.
- Liquidity valueOne of the two scores that fix a commodity's weight in an Indian commodity index — the average trading volume of its futures over the last 12 months.
- Maximum tenorThe 12-month ceiling on a commodity index derivative — an index futures contract may not run longer than 12 months, and index options are permitted up to 12 months of expiry.
- Price-based indexAn index whose constituent weights stay fixed for the year, so the level moves only when prices move — how every Indian commodity index works, as against volume-based equity indices.
- Production valueOne of the two scores that fix a commodity's index weight — the average value of deliverable supply over the past five financial years, where deliverable supply is production plus import.