The Bid & Ask

Quotations, Dispatches, and the Daily Tape

Thursday, August 13, 2026

Rejected thesis

Cross-sector momentum

The result

Thesis (marginal): Rank the 11 SPDR sector ETFs by 6-month return; top-ranked sectors continue to outperform bottom-ranked sectors over the next 1-6 months. Classical sector-level momentum (Asness 1997).

Code: research/cross_sector_momentum_validate.py Report: research/cross_sector_momentum_report.json (n=498)

Why we're parking it: Edge is in the right direction (top beats bottom) but small and only marginally significant.

Horizon Top mean Bot mean Spread t-stat
21 d +1.11 % +1.04 % +0.06 pp +0.11
63 d +3.24 % +2.45 % +0.79 pp +0.87
126 d +7.00 % +4.84 % +2.16 pp +1.71

Sector momentum exists but the magnitude doesn't justify a single-name position. It works as a portfolio overlay (long top 3 sectors via ETF basket, rebalance monthly) but doesn't generate per-name watch-list signals.

Verdict: Not added. Reasonable passive overlay, not a watch-list trade.


At a glance
Sample498
Validatorresearch/cross_sector_momentum_validate.py
VerdictRejected

Every result here is reproducible from the script named above. Reports are in the repository.

Other rejected theses