Understanding Risk-Adjusted Returns: Why Return Alone Tells You Nothing

Raw investment returns are seductive. A fund manager who claims 20% returns last year sounds dramatically more impressive than one who delivered 10%. But without understanding the risk taken to achieve those returns, comparing them is meaningless — and potentially dangerous.

Risk-adjusted return thinking is the foundation of professional investment analysis. It underpins the asset allocation decisions of pension funds, endowments, and family offices. And for individual international investors making decisions about where to place substantial wealth, it is not optional sophistication — it is basic investment hygiene.

This guide explains the key risk-adjusted return metrics, why they matter, and how to use them practically in portfolio construction and manager evaluation.

Why Raw Returns Tell You Nothing

Imagine two investment strategies over the same period:

• Strategy A: 12% annual return, but experienced a 45% peak-to-trough drawdown at one point and involved holding a concentrated portfolio of speculative small-caps.
• Strategy B: 10% annual return, with a maximum drawdown of 12% and a broadly diversified portfolio of quality global equities.

Which is the better strategy? Almost certainly Strategy B — unless you have an extremely long time horizon, iron nerves, and no liquidity requirements. Strategy A's additional 2% annual return came with far more than 2% of additional risk.

The problem is that when performance tables are published, they typically show only the headline return. The risk embedded in that return is buried in the small print, if disclosed at all.

The Sharpe Ratio: Return Per Unit of Risk

The Sharpe ratio, developed by Nobel laureate William Sharpe, is the most widely used measure of risk-adjusted return. Its formula is:

Sharpe Ratio = (Portfolio Return − Risk-Free Rate) ÷ Standard Deviation of Returns

Breaking this down:

• The risk-free rate is typically the return on short-term government bills (UK 3-month gilts, US T-bills). This is the return you could earn with zero risk.
• Standard deviation measures how much the portfolio's monthly or annual returns vary around their average — the higher the standard deviation, the more volatile the portfolio.

A Sharpe ratio above 1.0 is generally considered good. Ratios above 2.0 are excellent and relatively rare. Ratios below 0.5 over long periods suggest the return does not adequately compensate for the risk.

Using Sharpe ratios in practice: When comparing two funds or strategies with similar investment objectives, the Sharpe ratio is far more informative than raw return. A fund with a 9% return and Sharpe ratio of 1.2 is almost certainly a better investment than one with an 11% return and Sharpe ratio of 0.6.

One limitation: the Sharpe ratio treats upside and downside volatility equally. In practice, most investors do not object to upside volatility — it is downside volatility that causes distress and leads to poor behavioural decisions.

The Sortino Ratio: Penalising Only Downside Risk

The Sortino ratio addresses the Sharpe ratio's limitation by using only downside deviation in the denominator — it measures the return per unit of harmful volatility, ignoring the upside volatility that investors welcome.

Sortino Ratio = (Portfolio Return − Risk-Free Rate) ÷ Downside Deviation

The Sortino ratio is particularly useful for strategies with non-normal return distributions — hedge funds, options strategies, and alternative investments often have return distributions that are skewed or have "fat tails." For these strategies, the standard deviation understates the true downside risk, making the Sharpe ratio misleading. The Sortino ratio gives a cleaner picture.

As a rule of thumb: when evaluating traditional equity or bond funds, the Sharpe ratio is sufficient. When evaluating alternative strategies with complex return profiles, use the Sortino ratio alongside the Sharpe ratio.

Maximum Drawdown: The Real-World Stress Test

Maximum drawdown (MDD) measures the largest peak-to-trough decline an investment has experienced over a given historical period. If a portfolio reached a peak value of £100,000 and subsequently fell to £60,000 before recovering, the maximum drawdown was 40%.

Maximum drawdown is critically important for:

Retirees and near-retirees. Sequence of returns risk — the risk of experiencing a large loss at the beginning of or during retirement — can permanently impair a retirement plan. A 40% drawdown early in retirement, combined with regular withdrawals, may never fully recover.

Investors with short or medium time horizons. If you have a specific spending goal in five to seven years, a strategy with a historical maximum drawdown of 50% is inappropriate regardless of its long-run return.

Psychological sustainability. Very few investors genuinely behave rationally through a 40–50% drawdown. In practice, many sell at or near the bottom and do not benefit from the subsequent recovery. A strategy with a lower maximum drawdown may be more achievable — more likely to actually deliver its theoretical return — because investors are more likely to stay invested.

When evaluating a fund or strategy, always ask: "What is the worst loss I could have experienced if I had invested at the worst possible time, and how long did it take to recover?"

Beta: Market Sensitivity

Beta measures an investment's sensitivity to movements in a reference market (usually a broad equity index like the S&P 500 or FTSE All-World):

• Beta of 1.0: The investment moves in line with the market.
• Beta of 0.5: The investment typically moves half as much as the market in either direction — less risk, less upside.
• Beta of 1.5: The investment is 50% more volatile than the market — higher risk, higher potential upside.
• Beta of 0 or negative: The investment has little or no correlation to the market (cash, some hedge strategies) or moves opposite to it (certain short-selling strategies).

In a portfolio context, understanding the aggregate Beta of your holdings tells you how much market risk you are carrying. A portfolio with a weighted-average Beta of 0.7 would expect to capture approximately 70% of market upside and fall approximately 70% as much in a market decline.

Low-Beta strategies — quality equities, minimum volatility ETFs, balanced multi-asset funds — can reduce portfolio drawdowns while sacrificing some upside. This trade-off is appropriate for investors with shorter time horizons or lower risk tolerance.

How Private Equity and Hedge Funds Can Mislead on Risk

Illiquid assets — private equity, private credit, unlisted real estate, infrastructure funds — present a specific risk measurement problem. Because they are not traded daily, they are not "marked to market" continuously. Instead, valuations are updated quarterly or semi-annually based on estimates.

The result is that reported volatility looks artificially low. A private equity fund may report smooth, steadily rising valuations even as the public equity market underlying it falls 30%. This makes the Sharpe ratio of private equity look exceptional — but it is partly an artefact of the valuation methodology, not true economic risk reduction.

When markets genuinely seize up — as they did in 2008–2009 and briefly in March 2020 — the correlation between private and public assets rises sharply. Private equity funds struggle to exit positions, distributions slow, and the "volatility" that was hidden in smooth quarterly valuations becomes uncomfortably real.

Sophisticated investors account for this by "unsmoothing" private equity return data — adjusting the reported returns to estimate the true underlying volatility. The result typically reduces the risk-adjusted attractiveness of private assets, though not to zero.

Correlation and Portfolio Construction

The correlation coefficient measures how two investments move relative to each other. Values range from -1 (perfect inverse relationship) to +1 (perfect positive relationship). Zero means no relationship.

In portfolio construction, low or negative correlation between assets reduces overall portfolio volatility without necessarily reducing expected return — this is the mathematical foundation of diversification.

The classic example is the historical negative correlation between high-quality government bonds and equities. When equities fall in a risk-off event, investors typically buy government bonds, driving their prices up. Holding bonds alongside equities reduced portfolio volatility without proportionally reducing return — until 2022, when both fell simultaneously as interest rates rose sharply.

This illustrates a critical point: correlations are not stable. They can change dramatically as the macroeconomic regime changes. Risk management based on historical correlations alone is insufficient; you must also think about the economic conditions under which historical correlations might break down.

The Efficient Frontier

Harry Markowitz's efficient frontier is the mathematical framework underlying modern portfolio theory. It shows, for any given set of assets, the combinations that achieve the highest expected return for each level of risk (or the lowest risk for each level of expected return).

Portfolios on the efficient frontier are by definition the best combinations available. Portfolios below it are suboptimal — the same return is available at lower risk, or higher return is available at the same risk.

In practice, the efficient frontier is estimated using historical returns, volatilities, and correlations — all of which are imprecise guides to the future. The frontier shifts as economic conditions change. But the concept remains valuable: it reminds investors that portfolio construction is about combining assets in ways that maximise return per unit of risk, not just about picking the highest-returning individual assets.

Using Risk-Adjusted Thinking in Practice

A practical rule for international investors evaluating any investment opportunity:

Before asking "what is the expected return?", ask "what is the return per unit of risk, and what would I lose in the worst realistic scenario?"

Specifically:

• Ask for the Sharpe or Sortino ratio of any fund, strategy, or manager you are considering. Compare it against relevant benchmarks over the same period.
• Ask for the maximum drawdown and the recovery period — how long it took to reach a new high after the worst loss.
• Ask for the correlation of the investment to your existing holdings — genuine diversification requires low correlation, not just a different label.
• Be sceptical of illiquid alternatives that report unusually smooth returns and low volatility. Understand the valuation methodology before assuming the risk is genuinely low.

How Global Investments Can Help

At Global Investments, we evaluate every investment recommendation on a risk-adjusted basis, not simply on headline return. We use Sharpe ratios, drawdown analysis, and correlation matrices as standard tools in our portfolio construction process.

For internationally mobile investors, understanding the risk embedded in each holding is particularly important — currency risk, liquidity risk, and political risk can amplify the underlying investment risk significantly. We help you see the complete risk picture before committing capital.

Please note that all investments carry risk. Past risk metrics are not a reliable guide to future risk. The value of investments can fall as well as rise, and you may receive back less than you invest. This guide is for information purposes only and does not constitute personalised financial advice. Models and frameworks described are illustrative — seek professional advice relevant to your specific circumstances.