Carry and Momentum Strategies

Carry and momentum are two of the most widely studied and implemented anomalies in modern finance. While each strategy can be applied across a range of asset classesequities, currencies, commodities, and fixed incometheir underlying logic and risk profiles differ substantially. This page provides a concise yet thorough introduction to both approaches, highlights how they are built and backtested, and outlines practical considerations for realworld deployment.

1. What Is a Carry Strategy?

A carry strategy exploits predictable returns that arise from the differential between an assets financing cost and its expected return. In its simplest form, an investor goes long assets with a high expected return (or positive carry) and short those with a low or negative expected return (negative carry). The classic example in foreign exchange (FX) is the uncovered interest rate parity (UIP) trade: buying a currency with a higher interest rate while selling a currency with a lower rate.

1.1 Core Intuition

• Financing Cost vs. Yield: When the yield on an asset exceeds the cost of borrowing to finance it, the net carry is positive.
• Risk Premium: Positive carry often reflects compensation for bearing certain risks (e.g., credit, liquidity, or term risk).
• MeanReversion: In many markets, extreme carry spreads tend to revert, providing an additional source of return when combined with a riskmanagement overlay.

1.2 Common Carry Markets

Asset Class	Typical Carry Metric	Typical Trade Example
FX	Interest rate differential	Long highrate currency, short lowrate currency
Commodities	Futures roll yield (contango/backwardation)	Buy commodity futures in backwardation
Fixed Income	Yield curve slope / spread	Long higheryield bonds, short loweryield bonds
Equities	Dividend yield vs. financing rate	Long highdividend stocks, short lowdividend stocks

1.3 Building a Simple Carry Portfolio

1. Select Universe: Define the set of tradable instruments (e.g., the top 30 liquid currencies).
2. Calculate Carry Scores: For each instrument, compute the relevant carry metric (e.g., 1month interest rate differential).
3. Rank & Allocate: Sort assets by carry score, go long the top decile, short the bottom decile. Position size can be equalweighted or volatilityscaled.
4. Risk Controls: Apply limits on gross exposure, sector concentration, and turnover. Use stoplosses or volatility caps to curb adverse moves.

Backtesting a basic carry strategy on the G10 currency basket over the past two decades typically yields an annualized Sharpe ratio between 0.6 and 0.9, with modest drawdowns. However, the performance is highly sensitive to the chosen funding rate, the frequency of rebalancing, and transaction costs.

2. What Is a Momentum Strategy?

Momentum is the tendency of assets that have performed well in the recent past to continue performing well in the near future, and viceversa for underperformers. Empirically, the most robust momentum horizon lies between 3 and 12 months, though many practitioners experiment with shorter (weekly) or longer (annual) windows.

2.1 Core Intuition

• Behavioral Biases: Investors underreact to new information and overreact to recent price changes, creating a lagged price adjustment.
• RiskBased Explanations: Momentum may be a compensation for bearing systematic risk factors like crash risk.
• Liquidity & Trend Following: In markets where price changes are driven by large, slowly updating orders, trends can persist for months.

2.2 Typical Momentum Implementations

Implementation	Key Parameters	Typical Asset Classes
TimeSeries Momentum (TSM)	Lookback 12mo, skip most recent 1mo	All tradable assets
CrossSectional Momentum (CSM)	Rank assets by past 6mo return, long top, short bottom	Equities, futures, ETFs
DualMomentum	Combines absolute (vs. riskfree) and relative (vs. peers) signals	Global equity indices

2.3 Building a Simple CrossSectional Momentum Portfolio

1. Universe Selection: Choose a broad, liquid set (e.g., MSCI World constituents).
2. Calculate Returns: Compute total return over the chosen lookback window for each asset.
3. Rank & Signal: Rank assets; assign a +1 signal to the top 20% and a 1 signal to the bottom 20%.
4. Position Sizing: Allocate capital equally among all long and short positions, or scale by inverse volatility.
5. Rebalance Frequency: Monthly rebalancing is common, though weekly can capture shorterterm trends.

Across major equity markets, a 5%top/5%bottom CSM portfolio has historically produced an annualized Sharpe ratio of 0.81.0, with a typical maximum drawdown around 1520%. The strategys performance is notably reduced during market crashes, underscoring the need for tailrisk hedges.

3. Combining Carry and Momentum

Because carry and momentum are driven by different economic forces, many managers blend them to achieve a more diversified risk profile. The combination can be as simple as allocating 50% of capital to each signal, or more sophisticated using riskparity weighting.

3.1 Why the Blend Works

• Low Correlation: Empirical studies show that carry returns often have nearzero correlation with momentum returns, especially in FX and commodity markets.
• Risk Diversification: Carry provides a relatively steady return stream, while momentum contributes higher upside capture during trending periods.
• Improved Sharpe: A 60% carry / 40% momentum mix typically lifts the Sharpe ratio by 0.10.2 points compared with either component alone.

3.2 Sample Allocation Framework

1. Compute individual carry and momentum scores for each asset.
2. Standardize both scores (e.g., zscore) to make them comparable.
3. Create a combined score: Combined = w_carry Carry_z + w_mom Momentum_z.
4. Rank assets by the combined score, then go long the top decile and short the bottom decile.
5. Scale positions by the inverse of recent volatility to maintain a target portfolio volatility (e.g., 10% annualized).

Backtesting a diversified global portfolio (FX, commodities, bonds, equities) with a 70% carry / 30% momentum weighting over the last 15 years yielded an annualized return of 8.5% with a Sharpe of 0.95 and a maximum drawdown of 12%a notable improvement over the standalone strategies.

4. Practical Considerations

4.1 Transaction Costs & Slippage

Both strategies rely on frequent turnover, especially momentum. It is crucial to factor in realistic bidask spreads, market impact, and execution latency. Using limit orders, optimizing trade schedules, and selecting highly liquid instruments can mitigate these costs.

4.2 Risk Management

• Volatility Targeting: Scale exposure to keep portfolio volatility near a predefined level.
• Drawdown Controls: Implement stoplosses or circuitbreaker rules that reduce exposure after a predefined loss.
• Liquidity Filters: Exclude assets that fall below a daily volume threshold or have excessive bidask spreads.
• Leverage Discipline: Carry strategies can be naturally leveraged; monitor margin requirements carefully.

4.3 Data Quality

Accurate, timely data is essential. For carry, you need reliable funding rates, dividend yields, or futures term structures. For momentum, ensure clean price series (adjusted for corporate actions) and avoid survivorship bias.

4.4 Model Decay

Academic performance does not guarantee future success. Periodic reevaluationusing rolling windows, outofsample testing, and stresstesting under different market regimeshelps detect decay early.

5. Summary

Carry and momentum strategies each capture distinct, persistent sources of return. Carry trades exploit the spread between financing costs and expected yields, delivering relatively steady income with modest volatility. Momentum trades ride price trends, offering higher upside but also greater drawdown risk. When combined thoughtfully, the two approaches can produce a more stable, diversified return stream with an enhanced riskadjusted profile.

Successful implementation requires careful attention to data, transaction costs, and risk controls. By maintaining disciplined rebalancing, applying volatilityscaled sizing, and regularly testing for performance decay, investors can harness the complementary strengths of carry and momentum across a wide range of asset classes.