Factor Investing and Smart Beta: A Guide for International Investors

What Is Factor Investing?

Factor investing is the practice of systematically tilting a portfolio toward characteristics — "factors" — that academic research has identified as persistent drivers of returns above a broad market benchmark. It sits between passive index investing (which simply buys the market at market-cap weights) and traditional active management (which relies on individual fund manager judgment).

The foundational insight is that markets are not random. Certain systematic characteristics — a stock being cheap relative to its fundamentals, trending upward in price, highly profitable, or small — have historically been associated with higher long-run returns across multiple geographies and time periods. These are not one-off observations; they have been documented in decades of academic research across thousands of stocks globally.

Factor investing operationalises this insight: build a rules-based portfolio that consistently overweights stocks with the desired characteristics, and capture the factor premium over time.

This guide covers the five most widely accepted equity factors, the evidence behind each, how to access factors via UCITS ETFs, the cyclical nature of factor performance, and the limitations that investors should understand before allocating capital.

The Academic Foundations

The intellectual origins of factor investing trace primarily to the work of Eugene Fama and Kenneth French, whose 1992 paper extended the Capital Asset Pricing Model (CAPM) to incorporate two additional factors beyond market beta: size (small cap premium) and value (value premium). Their three-factor model has been extended by Mark Carhart (adding momentum) and subsequently by Fama and French themselves (adding profitability/quality and investment factors).

The key empirical claim: portfolios that systematically tilt toward small cap, value, momentum, quality, and low volatility stocks have delivered higher risk-adjusted returns than the broad market over long historical periods, across multiple geographies. The premiums are not large in any single year, but compound meaningfully over decades.

The Five Core Factors

1. Value

Definition: Stocks that are cheap relative to fundamental metrics — price-to-earnings, price-to-book, price-to-cash flow, enterprise value-to-EBITDA. The value premium is the tendency for cheap stocks to outperform expensive ones over the long run.

Economic rationale: Value stocks are cheap for a reason — the market has extrapolated poor recent performance, depressed earnings, or unfavourable business trends into the future. When these companies recover, or when their pessimism is simply not justified, the rerating of their multiples generates strong returns.

Historical evidence: One of the most robust and long-documented factor premiums, dating back to Ben Graham's era. However, the value factor experienced a dramatic decade-long underperformance period from around 2009 to 2020 as growth (technology) stocks dominated. It recovered strongly in 2021–2022 when rising rates hurt long-duration growth stocks and made cheap, cash-generative value stocks relatively more attractive.

Practical risk: Value strategies can underperform growth strategies for very long periods. Investors who cannot sustain conviction through a decade of underperformance should not pursue a pure value tilt.

2. Momentum

Definition: Stocks that have risen in price over the past 12 months (excluding the most recent month) tend to continue rising in the near term. Momentum strategies buy recent winners and sell (or short) recent losers.

Economic rationale: Behavioural finance suggests momentum reflects the slow diffusion of information and investor under-reaction to news — good news is not fully priced in immediately, so stocks continue to drift upward. Additionally, trend-following institutional flows compound initial price movements.

Historical evidence: Among the strongest and most consistent factor premiums historically. Documented across international equity markets, bond markets, commodity markets, and currencies.

Practical risk: Momentum strategies are susceptible to sharp "momentum crashes" — when a trend reverses rapidly, momentum portfolios (which hold recent winners) experience simultaneous sharp losses across many positions. The March 2020 COVID crash was a severe momentum crash event. Momentum requires high portfolio turnover (positions updated monthly), generating higher transaction costs than other factors.

3. Quality

Definition: Stocks of high-quality companies — typically measured by profitability (high return on equity, return on invested capital), earnings stability (low earnings variability), low leverage (low debt), and strong cash flow generation.

Economic rationale: High-quality companies are structurally more resilient, more capable of compounding returns over time, and less likely to suffer severe drawdowns in downturns. The market tends to undervalue sustainable quality because it is more exciting (and easier to sell) to focus on growth, recovery, or momentum stories.

Historical evidence: Solid long-run premium, particularly defensive outperformance during market downturns. Quality tends to do well in late-cycle and recessionary environments. It is often the most consistent factor in terms of Sharpe ratio.

Practical risk: Quality stocks tend to be more expensive than value stocks. In a strongly risk-on market, cheap cyclicals can dramatically outperform high-quality defensives for extended periods.

4. Low Volatility

Definition: Stocks with lower than average historical price volatility have — counterintuitively — generated better risk-adjusted returns than high-volatility stocks.

Economic rationale (theoretical): The Capital Asset Pricing Model predicts that higher risk (volatility) should be rewarded with higher returns. Empirically, this does not hold for idiosyncratic (company-specific) volatility. Behavioural explanations include: institutional investors' preference for "lottery ticket" high-volatility stocks drives their overvaluation; and investor attention biases toward exciting, volatile names.

Historical evidence: Very strong risk-adjusted returns (high Sharpe ratio), particularly through bear markets. Low-volatility portfolios typically have smaller drawdowns and faster recovery.

Practical risk: Low-volatility strategies tend to be concentrated in specific sectors (utilities, consumer staples, healthcare) and can underperform significantly in strong bull markets. They also have interest rate sensitivity — many low-volatility stocks are in high-yield, bond-proxy sectors that are hurt by rising rates.

5. Size (Small Cap Premium)

Definition: Smaller companies (low market capitalisation) have historically delivered higher returns than large cap companies over the long run.

Economic rationale: Small companies have more room to grow; they are less well-researched by institutional analysts; they may access financing less efficiently (creating an opportunity for investors who can bear illiquidity). The premium partly compensates for the genuine additional risk of smaller companies.

Historical evidence: The original Fama-French finding. The premium has been inconsistent in recent decades, particularly in the US, where large cap technology dominance has compressed the small cap premium. In international markets, small cap premiums have been more persistent.

Practical risk: Small cap stocks are less liquid than large caps, meaning transaction costs are higher and capacity for large allocations is limited. Small cap indices also include very poor-quality businesses alongside the quality small caps that generate the premium — quality-adjusted small cap exposure is more robust than raw small cap index exposure.

Factor ETFs: Key UCITS Options

Major UCITS factor ETFs available as of 2026:

Value:

• iShares Edge MSCI World Value Factor UCITS ETF (IWVL)
• Invesco MSCI World Value UCITS ETF

Momentum:

• iShares Edge MSCI World Momentum Factor UCITS ETF (IWMO)
• Xtrackers MSCI World Momentum Factor UCITS ETF

Quality:

• iShares Edge MSCI World Quality Factor UCITS ETF (IWQU)
• Xtrackers MSCI World Quality Factor UCITS ETF (XDEQ)

Low Volatility:

• iShares Edge MSCI World Minimum Volatility UCITS ETF (MVOL)
• Invesco S&P 500 Low Volatility UCITS ETF

Multi-Factor:

• iShares Edge MSCI World Multifactor UCITS ETF (FSWD): combines value, quality, momentum, and small cap.
• Ossiam Shiller Barclays CAPE US Sector Value UCITS ETF: sector-level CAPE-based factor exposure.

TERs on factor ETFs are typically 0.20–0.40% — higher than plain vanilla market cap index ETFs but lower than traditional active funds.

Factor Cycles and Long-Term Conviction

The most important thing to understand about factor investing is that factor premiums are cyclical — they go through extended periods of underperformance before recovering. Investors who lack the conviction to hold through underperformance periods will exit at the worst times, crystallising losses and missing recoveries.

The value factor's 2009–2020 cycle is the most prominent recent example. From the global financial crisis recovery to the COVID-19 crash, the MSCI World Value factor underperformed the MSCI World Growth factor by more than 100 percentage points cumulatively. Investors and commentators began questioning whether value as a factor was "dead" — whether the information economy had permanently changed the economics in favour of growth.

Then in 2021–2022, as interest rates rose and the long-term discount rates applied to high-multiple growth stocks increased, value recovered dramatically. Investors who had abandoned value in 2019 or 2020 missed the recovery.

Momentum's crashes occur regularly but are intense and short — March 2020 saw one of the sharpest momentum crashes on record. Investors who exited momentum positions at the crash locked in losses; those who stayed recovered within a few months.

The implication: factor investing requires a very long time horizon (ideally 10+ years), genuine conviction in the underlying rationale (not just backtested returns), and the psychological discipline not to abandon a strategy during its inevitable periods of underperformance.

Combining Factors for Diversification

Individual factors are cyclical and can underperform for extended periods. Combining multiple factors can reduce this volatility:

• Value + Momentum: These factors have historically had negative correlation — when value struggles (growth dominates), momentum tends to perform well in trending growth markets, and vice versa. A portfolio combining value and momentum blends their premiums while reducing the severity of each individual factor's underperformance periods.

• Quality + Value: Quality prevents the value portfolio from holding "value traps" — companies that look cheap because they are genuinely deteriorating businesses. Combining quality with value tilts toward cheap but fundamentally strong companies.

A multi-factor ETF does this mechanically in a single product. The trade-off is less transparency about how each factor is weighted and defined, and difficulty in attributing performance.

Factor Investing vs Active Management

A key question for international investors is: are we paying for active management when we could get the same factor exposures more cheaply through ETFs?

Research suggests that a significant portion of active fund outperformance can be explained by unintentional or deliberate factor exposures. A "stock picker" who systematically buys cheap, high-quality, small companies is, in part, capturing factor premiums — but at active management charges of 0.80–1.20%, compared with factor ETF charges of 0.20–0.40%.

Factor ETFs provide a transparent, systematic, lower-cost route to the same exposures. This does not mean active managers add no value — skilled managers may add genuine stock-selection alpha beyond factor exposure, particularly in less efficient markets — but investors should understand what they are paying for.

Limitations of Factor Investing

• Factors can underperform for very long periods — sometimes 5–12 years. Most investors lack the conviction to hold.
• Factor crowding can temporarily distort factor premiums and cause sharp drawdowns when large quantitative funds exit similar positions.
• Factor definitions vary between providers — two "value" ETFs may use very different metrics and have surprisingly different portfolios.
• Backtesting bias: Many published factor premiums suffer from overfitting (the factor was defined based on historical data, which inevitably shows a premium) and publication bias (factors that worked are published; those that didn't are not).
• Higher costs than plain vanilla: Factor ETFs are more expensive than broad market trackers. The net return improvement must exceed the cost difference.

How Global Investments Can Help

Global Investments works with internationally mobile HNW clients to assess whether factor tilts are appropriate within their portfolio construction — taking into account their investment horizon, conviction, and the current state of factor valuations and cycles.

For clients with long time horizons and the patience to hold through factor underperformance periods, a thoughtful allocation to value, quality, or multi-factor ETFs can improve portfolio efficiency. For clients who need predictable short-term outcomes, the cyclicality of factor returns is a meaningful risk.

To discuss factor investing and smart beta as part of your international portfolio strategy, contact our advisory team.

Capital is at risk. Factor investing involves risk including periods of significant underperformance relative to broad market indices. Past factor premiums are not a reliable indicator of future returns. Tax treatment depends on individual circumstances and may change. This article is for information purposes only and does not constitute personalised financial advice.