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·4 min read·BestFolio Research Team

Updated

Generalized Protective Momentum: how the breadth rule scales protection

Correction, 12 October 2026: this post first described the rule BestFolio's GPM ran until 10 October 2026: 13 assets with IEF counted as a risky one, protection always in SHV, and a protection share that jumped from about 62% straight to 100%, the "all-cash cliff" of the original title. That rule had drifted from Keuning and Keller's paper. GPM now follows the published rules, which scale protection in equal steps with no cliff, so the post was rewritten around them. The card figures below are the current ones.

Generalized Protective Momentum looks like a ranking strategy until breadth weakens. It scores 12 risky assets, selects 3 leaders, and then asks a separate question: how many assets have a positive score at all? The fewer there are, the more of the portfolio goes to crash protection, in equal steps, until at 6 or fewer the whole portfolio is protected.

Bar chart of GPM's crash-protection share against the number of its 12 risky assets with a positive score: 0% at 12, 17% at 11, 33% at 10, 50% at 9, 67% at 8, 83% at 7 and 100% at 6 or fewer
Keuning and Keller's published rule: protection rises by one sixth for each asset that drops below zero and reaches 100% at 6 or fewer positive scores.

The current BestFolio card for the standard GPM implementation covers 41.8 years, from January 1985 through October 2026. It reports 10.57% annualized return, a 0.86 Sharpe ratio, 8.36% volatility, and a -15.13% maximum drawdown. The modest return and low volatility fit the strategy's intended role: protection and portfolio ballast rather than a standalone return engine.

Step 1: score the universe

GPM's universe is 12 risky assets: US large, tech-heavy and small-cap stocks (SPY, QQQ, IWM), Europe, Japan and emerging markets (VGK, EWJ, EEM), real estate (VNQ), commodities (DBC), gold (GLD), high-yield and investment-grade corporate bonds (HYG, LQD) and long Treasuries (TLT). Each asset's raw momentum is the average of its 1-month, 3-month, 6-month and 12-month total returns.

The score is then adjusted by how correlated the asset has been with the equal-weight mix of all 12 over the last 12 monthly returns: score = momentum x (1 - correlation). An asset with strong momentum and a lower correlation receives more credit than another leader moving in lockstep with everything else. Keuning and Keller's design is not only looking for what has risen. It is looking for leaders that add something different.

Step 2: count positive scores

Let n be the number of risky assets with a positive score. The crash-protection share is (12 - n) / 6: nothing when all 12 are positive, one sixth more for each asset that drops out, half at 9, and the whole portfolio at 6 or fewer. The rest is split equally among the 3 highest-scoring risky assets.

The protection itself is not fixed. GPM scores IEF and short-term Treasuries (SHV) the same way and holds whichever scores higher, so when rates are falling the protection can be intermediate Treasuries rather than cash.

This gives the strategy 2 defensive behaviors. Weakening breadth scales protection upward while the portfolio still owns leaders. Breadth at half the universe or below sends the whole portfolio to protection.

Why the breadth rule helps

Relative momentum always finds a winner. In a broad decline, the best-ranked risky asset can simply be the one losing least. The positivity count stops that ranking machine from turning a bad universe into a confident allocation.

The rule also makes the strategy auditable. There is no discretion about whether the backdrop feels dangerous. A reader can reproduce the 12 scores, count the positives, and know the next allocation.

Where it can still hurt

Every step is still a threshold: each asset that crosses zero moves a sixth of the portfolio. Suppose several assets sit just above or below zero. A small data revision or a different month-end close can change the count and move a sixth or a third of the portfolio between risk and protection. The steps are even, so there is no single cliff, but nearby months can still look more different than they are.

That raises practical questions for any implementation. Are the inputs adjusted for distributions? Is the score computed from official month-end closes? Does the backtest trade on information that was available at the time? Does a 1-day delay change the historical switches? GPM's published rule is precise enough to test those questions, which is an advantage, but the clean rule does not remove the timing risk.

How I would use it

GPM's 10.57% annualized return should not be compared with a concentrated equity strategy as if the 2 were substitutes. Its 8.36% volatility and -15.13% maximum drawdown show a different job. In a blended portfolio, the question is whether GPM's defensive switches and low-correlation leaders improve the total allocation.

I would also watch the months when breadth sits near the middle of the universe. A backtest summary can tell us the long-run effect of the rule. The switch log tells us whether the investor could follow it through a cluster of rapid moves between risk and protection.

The design's best idea is simple: do not confuse the highest-ranked asset with a healthy opportunity set. GPM turns that idea into a rule anyone can check.

Explore Generalized Protective Momentum.

Past performance does not guarantee future results. Backtested results are hypothetical and do not represent actual trading.

Corrections

  • : Figures updated to the current cards. Sharpe and UPI are now measured above cash, see bestfolio.app/changelog. GPM's card now shows a 0.86 Sharpe and 8.36% volatility (were 1.18 and 8.22%); return and drawdown are unchanged.
  • : The 17 October 2026 restatement opened the GPM card in January 1985 (41.8 years); it now reports 10.57% a year and a -15.13% maximum drawdown.
  • : Card figures restated on 16 October 2026: early-1990s international and emerging-market history now uses index data instead of two actively managed funds. GPM's card now shows 9.70% a year, a 1.18 Sharpe and 8.22% volatility (was 9.65%, 1.17 and 8.25%); the maximum drawdown is unchanged.
  • : Card figure restated on 15 October 2026: volatility is now measured on observed prices, so months rebuilt from monthly data count at their month-end returns. GPM's volatility is now 8.25% (was 8.11%).
  • : The September 24, 2026 release corrected backtest history (PRITX replaces a Treasury fund in the 1989 to 1996 international-stock chain, 81 one-day price spikes removed, return-stacked stand-ins now pay financing) and every card was recomputed. The GPM standard card now reports 8.91% CAGR, 1.13 Sharpe, 7.59% volatility and -15.06% maximum drawdown (was 8.85%, 1.14, 7.52%, -15.07%).

Revision history

  1. Rewritten for GPM's published rules

    Since 10 October 2026 BestFolio's GPM follows Keuning and Keller's published rules: 12 risky assets, protection share (12 - n) / 6 with no all-cash cliff, protection in IEF or short Treasuries. The post described the old rule, so it was rewritten, with the current card (9.65% a year, Sharpe 1.17, -12.93% worst fall) and a new chart.

Figure sources

The strategy figures in this post were read from these published backtest runs. Each strategy page shows its latest run, which may differ.

  • gpm (gpm-standard), backtest run of 1985-01-01 to 2026-10-16. Engine drift-until-flip-v1, data version 30b2debc, published 2026-10-17.

Written with the help of AI tools and reviewed before publication.

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