Identify equities approaching S&P 500 / Russell addition or deletion thresholds; classify expected price impact
Flags stocks that may soon be added to, promoted within, or dropped from major indexes -- events that often bring forced buying or selling. It scores names on how closely their market cap, liquidity, and profitability track S&P 500 and Russell inclusion rules, excludes existing S&P 500 members, and merges in any platform-provided rebalance candidates with an expected flow direction. The output is a ranked list of addition/promotion alerts and deletion-risk flags, plus the next confirmed rebalance date when known. The index-inclusion price effect is documented but has weakened substantially in later studies, so candidates describe how close a name sits to the rules rather than forecasting a price move.
Anticipating index changes - a documented effect, and one whose predictability is also its weakness.
WHY INDEX CHANGES MOVE PRICES. Index funds hold what the index holds, so an addition creates a block of demand that is price-insensitive and time-concentrated, and a deletion creates the mirror. Shleifer (1986) and Harris and Gurel (1986) documented significant abnormal returns on S&P 500 inclusion announcements, and their competing interpretations are worth knowing: Shleifer read it as evidence of DOWNWARD-SLOPING DEMAND CURVES for stocks, a direct challenge to the idea that a security has one fundamental value at which any quantity clears, while Harris and Gurel read it as temporary price pressure that reverses.
THE EFFECT HAS WEAKENED SUBSTANTIALLY in later work. Greater anticipation, deeper liquidity and more index-arbitrage capacity are the leading proposed explanations - which matters directly for this analysis, because it is itself an attempt to anticipate, and the more participants do so the smaller the remaining effect.
WHY THE CRITERIA ARE SCREENABLE AT ALL. Index inclusion is rules-based enough to model. S&P's criteria include US domicile, a float and liquidity minimum, and PROFITABILITY - positive earnings in the most recent quarter and in the sum of the trailing four - which is why profitability appears in the score here. Russell reconstitution is essentially a market-capitalisation ranking at a scheduled date. So the inputs are public and the rules are known.
BUT NOTE THE ASYMMETRY BETWEEN THE TWO. Russell's reconstitution is mechanical and dated, which makes it highly anticipatable - and correspondingly crowded, since everyone can run the same screen. S&P additions are decided by a COMMITTEE, which retains discretion: meeting every criterion makes a company eligible, not selected. A screen can identify candidates and cannot predict a committee.
EXCLUDING EXISTING S&P 500 MEMBERS is correct - they cannot be added - and shows the screen is about the transition rather than the state.
THE FRONT-RUNNING PROBLEM IS THE DEEPEST ISSUE. If an addition is widely predicted, the price moves BEFORE the announcement, and the buyer at announcement is buying from those who anticipated. That is the mechanism by which the documented effect decays, and any strategy built on it is racing participants who run the same rules with more capital and faster execution.
The scoring weights and thresholds are our own convention.
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