How to read index rebalance flows

Start with the event and the edition

An index addition, deletion or weight change can alter the holdings required by funds tracking that index. A rebalance flow model translates those changes into estimated buying and selling. The estimate depends on inputs such as index weights, shares, prices and assets tracking the index.

Before comparing stocks, identify the index event, expected implementation date and model edition. A figure from an earlier workbook describes the assumptions available at that time. It may change as inputs or index announcements change. Check the provider's current notice rather than treating a historical example as a current event.

Read net and gross together

A security may face estimated buying in one index and selling in another. Net flow describes the balance after those opposing estimates are offset. Gross flow preserves the activity on both sides.

Check each workbook's definition of gross flow before comparing reports. A small net number can coexist with large opposing estimates. Neither number tells you exactly how much will trade: institutions may offset positions internally or implement changes at different times.

Keep dollars and shares in view

Dollars help compare the scale of estimated demand across securities. Shares make that estimate easier to compare with stock-level trading volume. Converting between them requires a reference price, so a price change can affect the dollar estimate even when the share estimate is unchanged.

Look at the units and price date before comparing two rows or two editions. A table expressed in millions of dollars should not be read as a table of shares.

Put the estimate beside liquidity and float

Average daily volume (ADV) measures normal trading activity over a stated lookback period. Dividing estimated shares by ADV gives a scale comparison. For example, an illustrative estimate of six million shares against two million shares of ADV equals three times ADV. It does not mean the stock will trade that amount on the implementation day, or that the position can be executed in three days.

Float provides a different comparison: the shares treated as available for public trading under the applicable definition. Estimated demand as a percentage of float can help distinguish stocks with similar dollar flows but different available supply. Check both definitions and their dates; ADV and float are not interchangeable measures.

Compare several measures before drawing a conclusion

Price impact also depends on positioning, liquidity and how other participants respond. A flow estimate is a research input, not confirmed fund orders, a forecast of trading volume or a guaranteed direction of price movement.

See the measures in the QSG workbook

The QSG Index Rebalancing research page shows actual historical workbook excerpts with net and gross flows, ADV and float comparisons. Read the source notes and assumptions alongside the screenshots, then follow the publication link for the context of that edition.

For index-provider background, see FTSE Russell's explanation of reconstitution and portfolio rebalancing. The provider's methodology and notices remain the source for official index changes.