Currency Momentum: Why Trends Persist in FX
Currency momentum is the systematic tendency for a currency that has been strong over the past several months to remain strong, and for a weak currency to remain weak. It is one of the most replicated findings in international finance, and understanding why it exists helps you read the macro landscape — not just pick a direction.
Momentum is not a vague observation. It is a measurable, academically documented phenomenon with a well-established literature spanning equities, bonds, commodities, and currencies. In FX, it has been earning excess returns in research samples dating back to the 1970s.
- Currency momentum is the tendency for recent winners to keep winning and recent losers to keep losing — typically over a one-to-twelve-month look-back window.
- A landmark study by Menkhoff, Sarno, Schmeling and Schrimpf (2012) found cross-sectional spreads of up to 10% per annum between past winner and loser currencies.
- The effect is not fully explained by standard risk factors and survives across a wide range of currencies and time periods.
- Momentum can be cross-sectional (rank currencies against each other) or time-series / trend-following (is this currency trending relative to its own history?).
- Momentum and carry are related but different: carry earns an interest differential; momentum earns a trend premium. They can reinforce or contradict each other.
What is currency momentum?
Currency momentum is the FX equivalent of the equity momentum factor first systematically documented by Jegadeesh and Titman (1993), who found that US stocks that had outperformed over the prior 3–12 months continued to outperform over the next 3–12 months. Researchers quickly asked: does the same hold for exchange rates?
The answer is yes. A currency that has appreciated against a basket of peers over the past six to twelve months tends to continue appreciating. Conversely, a currency that has depreciated tends to keep falling. The signal is not perfect — it reverses at multi-year horizons as mean reversion takes over — but within the medium-term window, it is robust enough to have earned consistent excess returns in out-of-sample tests across decades and geographies.
The academic evidence: what Menkhoff et al. found
The definitive paper on FX momentum is Menkhoff, Sarno, Schmeling and Schrimpf (2012), published in the Journal of Financial Economics (volume 106, pages 660–684). Using data on 48 currencies from 1976 to 2010, they found:
- A cross-sectional spread of up to 10% per annum between the top and bottom quintiles of currencies ranked by past return.
- The momentum effect is strongest at one-month to twelve-month look-back horizons and reverses at horizons beyond four years.
- Returns are not explained by standard risk factors such as equity market risk, carry, or volatility exposure.
- The effect is partially eroded by transaction costs, meaning institutional players capture more of it than retail traders.
- Performance is consistent with investor under-reaction and over-reaction — price adjusts slowly to new information, then overshoots.
This built on earlier work by Asness, Moskowitz and Pedersen (2013), who showed that value and momentum premia appear together across eight asset classes — including currencies — and are negatively correlated with each other, suggesting they represent distinct risk premia.
Cross-sectional vs time-series momentum
There are two flavours of currency momentum, and they answer different questions.
| Cross-sectional momentum | Time-series momentum (trend) | |
|---|---|---|
| Question | Which currencies are strongest relative to each other? | Is this currency trending relative to its own history? |
| Method | Rank all currencies by past return; long top quintile, short bottom quintile | Compare each currency's return to its own historical distribution |
| Signal | Relative ranking | Absolute direction |
| Best for | Portfolio construction (pair selection) | Trend-following, single-pair directional conviction |
| Key paper | Menkhoff et al. (2012) | Moskowitz, Ooi and Pedersen (2012) — time-series momentum across asset classes |
For macro FX analysis, cross-sectional momentum is particularly useful because it maps directly onto the "which currency is stronger" question. When the PIPTHEORY Macro Currency Strength Meter shows USD rising week after week and JPY falling, that is a visual representation of cross-sectional momentum in the making.
Why momentum persists: three theories
Researchers have proposed three primary explanations for why prices continue trending in FX rather than immediately reflecting all available information.
- Under-reaction Investors and institutions absorb new information slowly. A central bank hawkish pivot or a strong GDP print causes an initial price move, but full repricing takes weeks or months as analysts update models, funds rebalance, and hedgers adjust positions. The delayed adjustment creates a trend that momentum strategies exploit.
- Herding and over-reaction As a trend becomes visible, more investors chase it. This momentum-chasing itself drives further price movement — sometimes past fundamental value. Eventually the over-extension corrects, which is why momentum returns at very long horizons turn negative (mean reversion). The two phases combined produce the momentum-then-reversal pattern seen in the data.
- Limits to arbitrage Even if sophisticated traders see the mispricing, correcting it is costly. Transaction costs, funding constraints, career risk for fund managers going against a trend, and the time uncertainty of when the trend reverses all act as barriers. Carry traders, for instance, cannot simply arbitrage away FX trends because the short side requires holding a depreciating position that may keep depreciating before it recovers.
Momentum vs carry: how they interact
Carry and momentum are the two most studied return premia in FX, and they are related but distinct.
Asness, Moskowitz and Pedersen (2013) found that value and momentum are negatively correlated across all asset classes, and carry is often positively correlated with value (both identify mis-priced currencies). In practice this means:
- A currency with a high interest rate and rising price momentum is doubly favoured — carry and momentum agree.
- A currency with a high interest rate but falling momentum is a warning sign — carry says hold, momentum says the trend is turning. This divergence often precedes a carry crash.
That second scenario — fundamental and price divergence — is exactly the signal the PIPTHEORY meter is designed to surface. You can read more about how value and momentum combine in Value vs Momentum in Currencies: What the Research Shows, or about when carry and momentum diverge most dangerously in The Carry Trade Explained.
Momentum in the 8 major currencies: what to look for
For the eight currencies tracked by the PIPTHEORY meter, momentum manifests in the macro scores in two ways: a score that is consistently high (or low) over multiple weeks, and a score that is changing direction — which is where the most interesting opportunities and risks tend to cluster.
The bar chart above is illustrative. In a real momentum environment, the spread between the top-ranked and bottom-ranked currency is what matters — and the live meter updates that ranking every four hours based on macro fundamentals.
Applying momentum thinking to your macro view
Even if you never run a quantitative momentum strategy, the concept sharpens your macro analysis. When you look at a currency pair like GBP/JPY, asking "how long has this trend been running and what is driving it?" tells you whether you are riding early momentum, joining a mature trend, or chasing an extended move that is close to reversal.
For a framework that combines momentum with value measures such as real effective exchange rates, see Value vs Momentum in Currencies: What the Research Shows. For the positioning data that confirms whether momentum is crowded, see How to Read the COT Report for Currency Positioning.
Educational macro context only — not investment advice.