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Sp500 Inclusion Drift

Updated eventData needs: lowlong only

2004

Chen, H., Noronha, G., Singal, V. (2004). "The Price Response to S&P 500 Index Additions and Deletions: Evidence of Asymmetry and a New Explanation." Journal of Finance, 59(4), 1901-1929.

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In plain terms

When a stock is newly added to the S&P 500, it tends to keep drifting up for a month or two after the official inclusion date — index-tilted funds keep buying, and analyst coverage expands. Go long for 30-60 days post-inclusion.

How it works

Newly-included S&P 500 names enjoy persistent positive drift well past the index-fund mechanical buying window. Chen-Noronha-Singal document +1-2% gradual drift over 30-60 days post-effective as discretionary index-tilted funds rebalance and the new constituent earns analyst coverage. Distinct from the existing index_rebalance_drift family which captures the announcement-to-effective short-term front-run + reversal.

Live results

0 times picked on its own · 1 times inside a blend (1 beat the stock) · updated 2026-06-06

This strategy is a frequent ingredient in blends that combine a few strategies on one stock. It has contributed to 1 such blended picks (1 of which beat simply holding the stock). Picking it on its own is only one of the ways it shows up.

How its picks scored vs. buy & hold

Each pick is graded on a recent year it was never tuned on, against simply owning the same stock

Where its edge concentrates

Share of picks in each company-size group that beat buy & hold

How often it trades

Active vs. patient. Bars on the left mean it waits for rare setups; bars on the right mean it trades often

Return vs. buy & hold

How much each pick beat or trailed simply owning the stock over the test year (extreme microcap moves trimmed)

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Data dependencies

Daily prices
Adjusted-close OHLCV for every US-listed ticker; primary price feed.
Index rebalance events
A data feed this strategy reads, refreshed on its normal schedule.

Expected edge

Reported return: +1-2% over 30-60d
Tested over: T+1 to T+60d

+1-2% over 30-60d post-effective (CNS 2004 long-tail drift).

Example tickers where this is likely to fire

TSLA UBER DASH PLTR SMCI

Illustrative only, the signal fires based on the live data, not a fixed list.

Related families

Index-Rebalance DriftCompany Events & Earnings

When a stock is added to the S&P 500, index funds must buy it on the effective date — front-runners earn +8% by then. Symmetric -4% on deletions.

Index Inclusion DriftFilings, Insiders & Ownership

When a stock first shows up in a broad index ETF, it tends to drift up 3-5% over the next month as funds rebalance.

Index Deletion Reversal LongCompany Events & Earnings

When a stock is removed from a major index, the forced selling temporarily pushes the price too low. Wait 5 days for the press to finish, then go long for 2-6 months as the price partially recovers.

Explore Sp500 Inclusion Drift on alphactor.ai

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