Merger arb & special sits
Explore the deal terms and catalysts inside the weekly Deal Book.
Explore this research01 / THE RESEARCH
Index rebalancing.
See the flows.
Explore the estimated buying and selling behind an index event, with context for the timing and liquidity of the trade.
WHAT’S INSIDE
From an index change
to a trading event.
The useful question goes beyond whether a stock enters or leaves an index. It is how much trading the change could create, when it lands, and how large it is relative to normal liquidity.
Subscribe to QSG ResearchEvent timing
Follow the sequence from announcements to the trade date and the date an index change takes effect.
A view across indexes
Separate estimated net demand from total gross activity when several indexes trade the same stock.
A stock-level lens
Compare estimated dollars and shares with average daily volume and available float.
The underlying detail
Use the published workbook to move between the event overview, individual stocks and index-level activity.
PUBLISHED EXAMPLE
An addition is only part of the picture.
FLEX moved between S&P indexes at the June 18, 2026 close. These selected QSG estimates show how buying and selling can offset.
FLEX / Selected index flows
June 18, 2026 close · USD millions
| Index / measure | Change | Est. flow ($mm) |
|---|---|---|
| S&P 500 | Addition | +2,622.9 |
| S&P MidCap 400 | Deletion | −2,221.0 |
| Technology Select Sector | Addition | +390.0 |
| Net, all index trades | Net buy | +389.5 |
| Gross, all index trades | Before offsets | 6,918.5 |
Source: QSG’s index rebalance primer, published September 14, 2026. Historical estimates, not current orders or trading recommendations.
Read beyond the headline.
The full example puts each index trade alongside the combined result. Open the original research for the complete table, methodology and liquidity measures.
QSG RESEARCH ON SUBSTACK
Follow the next rebalance.
Find QSG’s index research and subscription options on Substack.