Why is duration-neutrality important in factor investing?

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AcadiFi · Accepted Answer

Duration-neutrality isolates the factor premium from bulk interest-rate risk, preventing performance attribution to broad market moves rather than the specific factor signal. If a value portfolio tilts long-duration because high-OAS bonds tend to have longer duration, then the portfolio's return contains a duration bet that dominates the value signal. In a rising-rate environment, this 'value portfolio' would lose money even if value stocks outperformed like-for-like.

Mechanism: when constructing a factor-tilted portfolio, compute weighted-average duration of overweight minus underweight legs. If the net duration exposure differs from benchmark, add or subtract Treasury futures (or cash Treasuries) to neutralize. A long 10-year Treasury future position of $X notional carries duration $Y per $1 million notional; size the overlay to offset factor-portfolio duration mismatch.

For Calderon at $6 billion: a value-tilted portfolio shows +0.4 years duration versus Bloomberg Agg; hedge by shorting 10-year futures equivalent to ~$200 million duration-dollars. Annualized factor alpha is now cleaner: the 0.8% outperformance is attributable to value signal rather than a duration bet that might or might not pay off.

Same logic for other exposures: neutralize credit beta (avoid loading factor returns on beta), sector concentration (avoid accidentally timing energy or banks), and currency (for global bond factors).

Evidence: Ilmanen et al. and AQR research show that 40-60% of apparent factor alpha in naive constructions disappears after neutralizing bulk exposures, highlighting that the remaining 'pure' factor premium is what investors should expect to earn repeatably.

Portfolios that deliberately take duration bets are not factor strategies; they are directional strategies branded as factor.

Why is duration-neutrality important in factor investing?

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