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Rule-Based Factor Investing vs. Traditional Discretionary Investing in Mutual Funds

In the diverse world of mutual funds, investment strategies often fall into two broad categories: rule-based factor investing and traditional discretionary investing. While both aim to maximise risk adjusted returns for investors, they approach the decision-making process quite differently.

Understanding the Strategies

Rule-based factor investing, often associated with smart beta strategies, operates on predefined algorithms that systematically select stocks based on set factors and factor parameters. These factors include quantitative measures such as company size, value, momentum, volatility and quality. This approach is designed to take advantage of the consistent, repeatable opportunities that certain characteristics provide in the market. For instance, a rule-based fund might target high quality profitable companies that exhibit high price momentum and are relatively undervalued, investing in them until they no longer meet the criteria.

In contrast, traditional discretionary investing doesn't adhere to a fixed algorithm but rather relies on the expertise and judgement of fund managers. These managers perform qualitative and quantitative analyses, drawing on their experience, insights, and the broader economic context to make investment decisions. This could involve detailed analysis of a company's management team, competitive advantages, market conditions, and potential for growth.

Decision-Making Processes

The decision-making process in rule-based factor investing is systematic and objective. It removes human bias from the equation, potentially providing more consistency and discipline. The rules are transparent, making it easier for investors to understand the strategy's decision-making process. Because the rules are set and do not change over time, it is possible to do backtesting over a long period of time which provides the ability to analyse the performance of the rules over a long historical period.

Traditional discretionary investing, however, is subjective and can be heavily influenced by the fund manager's convictions. This could potentially lead to biases or emotional decisions that may not always align with market performance. Nonetheless, the human element allows for nuanced understanding and the ability to pivot strategy based on real-time market insights. Here investors often look at the performance of the fund or the fund manager over the past long period to analyse a manager’s decisions and its impact.

Roles and Expertise

Rule-based investing relies heavily on quantitative models developed by data scientists and financial analysts. These professionals backtest algorithms against historical data to ensure they can generate high risk adjusted returns across various market conditions.

Traditional discretionary funds, conversely, rely on the acumen of seasoned fund managers who can interpret complex market data and news to identify investment opportunities. Fund managers are often supported by research analysts who provide information to enable the manager in portfolio decision making.

Performance and Risk

Performance between the two can vary significantly under different market conditions. More often than not, the two styles offer a diversification opportunity that can ease the impact of volatility over the short term while participating in equity growth over the long term.

Risk management is another differentiator. Rule-based strategies with their innate discipline and lack of human intervention can ensure that risks are limited to acceptable levels. Discretionary managers, meanwhile, may adjust their strategies based on their perception of risk, potentially allowing for more diverse risk outcomes.


Rule-based strategies typically afford investors a clear view of the investment process and criteria used in selecting the portfolio. Traditional discretionary investing is less predictable, as it may not always be clear why a fund manager chose a particular investment over another.

Historical Context and Evolution

Both investment styles have a rich history and have evolved over time. Rule-based strategies have become more sophisticated with the advent of big data, faster computing power and advanced analytics, while discretionary investing has benefited from increased global connectivity and real-time information flow. However, with markets becoming more efficient, the advantage that discretionary managers enjoyed earlier has been steadily shrinking.

In conclusion, rule-based factor investing and traditional discretionary investing in mutual funds each have their merits and drawbacks. Investors should carefully consider their unique attributes, including the decision-making processes, costs, and potential for risk and return, before deciding which investment style best suits their portfolio.

  Passive Traditional Active Rule-Based
No Active Investing Active Investing (Mostly Qualitative) Active Investing (Only Quantitative)
Objective Market/Index Return Generate Outperformance Generate Outperformance
Use of Factors Depends on the Benchmark Index Not very predominant Predominant
Portfolio Characteristics Same as Benchmark Different from Benchmark Different from Benchmark