A book-to-price portfolio can lose money because the characteristic stopped
forecasting, or because the holders of the same book all leave at once. Those
are different failures. Decay is a shrinking information coefficient. A crash
that comes from the short leg, while the long leg is fine, is a positioning
event. The factor taxonomy names short interest, active-manager holdings, and momentum as
trading-environment factors. This note uses them as diagnostics on the
factor-mimicking portfolio: who else holds it, and which leg breaks.
Learning objectives. By the end of this note you should be able to:
- list the short-interest ratios Paleologo treats as characteristics, and the four interpretations he records;
- define crowding through active-manager holdings, including how stale a 13(f) filing is;
- trace a deleveraging loop from an external shock to endogenous losses;
- locate the momentum crashes he describes on the short leg, including the early-2016 energy episode, without inventing a crash -statistic.
In this lesson
- Short interest is a position, not a valuation
- Holdings measure the crowd directly
- The crash that lives on the short leg
Before you start
- Factor decay
- Factor Taxonomy for Equity Long-Short Books
- Factor Risk Management: Tactical Limits, Strategic Constraints, and Systematic Hedging
The full lesson, with worked examples and exercise solutions, is for members.
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