Cross Asset Momentum

Cross-asset momentum is a systematic investing strategy that identifies and trades momentum signals across diverse asset classes simultaneously. The strategy buys assets that are outperforming and sells those underperforming over a trailing observation period (typically 3–12 months), applying the same principle—momentum begets more momentum—across stocks, bonds, commodities, currencies, and other instruments.

How cross-asset momentum works

A typical cross-asset momentum strategy tracks price momentum across multiple asset classes:

Step 1: Calculate momentum scores. For each asset (e.g., S&P 500, 10-year Treasury, crude oil, EUR-USD), calculate the total return over the past 12 months. Assets with high returns rank high on momentum.

Example ranking (12-month returns):

• Crude oil: +35% → rank 1 (strongest momentum)
• S&P 500: +12% → rank 2
• Gold: −5% → rank 3
• 10-year Treasury: −8% → rank 4 (weakest momentum)

Step 2: Size positions inversely to volatility. Assets are position-sized to deliver equal risk contribution. A less volatile asset (Treasuries) might receive larger notional size than a volatile one (crude oil) to normalize risk.

Step 3: Construct portfolio. Long the top momentum assets (long crude oil, S&P 500). Short the bottom momentum assets (short Treasuries, short gold). Hold equally-weighted or risk-weighted.

Step 4: Rebalance regularly. Momentum scores degrade as time passes. Monthly or quarterly rebalancing updates the rankings and rebalances the portfolio.

Why momentum persists across asset classes

Behavioral drivers:

• Trend-following: Retail and institutional investors chase winners, pushing prices higher.
• Regime shifts: Once an uptrend begins, underlying factors (growth, inflation, risk appetite) often persist, sustaining the trend.
• Momentum-chasing: Trend-following algorithms buy strength, reinforcing trends.

Technical factors:

• Gap-filling and overshoots: Prices often overshoot fundamentals, creating elastic-band reversals that take time to unwind.
• Volatility clustering: High-volatility regimes tend to persist, affecting multiple assets in tandem.

Cross-asset momentum exploits these dynamics globally. A commodity bull market (driven by emerging-market growth) can last 12+ months. Equities in those countries also outperform. Fixed income lags (rates rise). A momentum strategy captures this entire regime shift with a single systematic rule.

Cross-asset correlation structure

A key advantage of cross-asset momentum is diversification of momentum signals. Individual asset classes can have spurious momentum (mean reversion, not continuation). But across asset classes, momentum is more robust.

Example: In 2021–2022:

• Equities: Strong momentum in 2021 (bull market); momentum reversed sharply in 2022 (bear market).
• Bonds: Weak momentum in 2021; momentum reversed in 2022 (rising values as rates fell back).
• Commodities: Strong momentum throughout (inflation hedge); lagged in late 2022.

A pure equity-momentum strategy would have been whipsawed (bought at 2021 peak; exited at 2022 trough). A cross-asset momentum strategy, holding diversified signals, would have navigated the regime change more smoothly.

Implementation methods

Manual/discretionary: A trader reviews returns across asset classes and manually adjusts positions. Biased, slow, and not scalable.

Quantitative models: Automated systems calculate momentum, rank assets, and execute trades based on pre-programmed rules. Most practical.

Multi-factor strategies: Combine momentum with other factors (value, volatility, carry) to improve diversification and reduce drawdowns.

Risk management and regime-dependence

Momentum strategies excel in strong trending markets but falter in choppy, mean-reverting conditions.

Bull market 2017: Cross-asset momentum thrived. Nearly all assets drifted higher; momentum signals were consistent and durable.

Choppy market 2016: Volatility spikes, reversals, and sector rotations undermined momentum signals. Strategy underperformed.

Risk management tools:

• Volatility normalization: Position sizing adjusts for asset volatility, preventing concentration in quiet, less-risky assets.
• Drawdown limits: If the strategy hits a max drawdown threshold (e.g., −15%), exposure is reduced or portfolio is rebalanced defensively.
• Sector/asset limits: Diversification rules ensure exposure is not concentrated in a single sector.
• Lag filters: To avoid buying rallies that are about to reverse, some strategies add a filter (e.g., only buy if momentum has been positive for 3+ months).

Comparison to single-asset momentum

Interaction with carry and value

Professional quant funds often blend momentum with other factors:

• Carry + Momentum: Buy high-yielding currencies (carry) that are also in uptrends (momentum). Bonds offering yield are good if also outperforming.
• Value + Momentum: Buy undervalued assets (value factor) that are also outperforming (momentum). Avoids “value traps” (cheap but getting cheaper).

These combinations reduce the risk that a single factor drives returns and improve risk-adjusted performance.

Recent performance and debate

2010–2021: Cross-asset momentum was a high-performing strategy, generating 5–8% annualized returns with low correlation to bonds and equities.

2022–2024: Performance has been mixed. The rapid normalization of policy rates caused momentum reversals across asset classes. Strategies that relied on 12-month lookbacks were whipsawed.

Academic debate: Some researchers argue momentum effects are decaying as more capital flows into systematic strategies, causing crowding and mean reversion. Others contend that regime-adaptive momentum (shortening lookback periods in choppy markets) mitigates this.

Global and emerging-market applications

Cross-asset momentum applies globally:

• Developed markets: Low-volatility strategies work well; momentum signals are cleaner.
• Emerging markets: Higher volatility but strong trend-following opportunities. Currency momentum adds complexity (FX carry + momentum).
• Commodities: Robust momentum in commodity-exporting countries (Brazil, Russia) where growth is tied to commodity prices.

Practical considerations for investors

For institutional investors: Quant funds (e.g., Winton, D.E. Shaw) implement cross-asset momentum at scale. Many offer retail-accessible funds or SMAs (separately managed accounts) with momentum or multi-factor mandates.

For retail investors: Direct implementation is complex. Retail options:

• Multi-asset ETFs: Broad diversified portfolios that may embed some momentum logic.
• Momentum-focused ETFs: Some focus on single-asset momentum (e.g., stock momentum); fewer track multi-asset momentum.
• DIY: A disciplined investor can track 5–8 key assets (S&P 500, Nasdaq, Treasuries, crude oil, gold, EUR-USD, etc.) and rebalance quarterly based on returns.

Drawdowns and tail risk

Momentum strategies can suffer severe drawdowns when trends reverse unexpectedly:

Example: February 2018 volatility spike. Momentum strategies that were long equities (trending up) and short volatility suffered losses. The VIX spike was a “momentum reversal” event.

Example: March 2020 COVID crash. Assets that had been in uptrends (stocks, high-yield bonds) reversed sharply. Momentum strategies took large losses before the strategies could adjust.

These drawdowns are the cost of momentum; they are often paired with large recoveries (the strategy catches the subsequent rebound).

Conclusion

Cross-asset momentum is a powerful systematic strategy that exploits price trends across multiple asset classes. It works best in trending markets with persistent regimes. It suffers in choppy, mean-reverting environments and during sharp reversals. Practitioners manage these risks through volatility normalization, diversification, and adaptive filters. For investors seeking returns less correlated to traditional long-only portfolios, cross-asset momentum remains a compelling tool, despite recent challenges.