Behaviorally Constrained Investment Process
Turn sound investing principles into rules that prevent biased decisions
- Difficulty
- Advanced
- Time to result
- ~ongoing to results
- Steps
- 6
- Confidence
- 97%
The framework separates enduring philosophy from changeable process. First, define the investment beliefs that should remain stable, such as focusing on quality growth at a sensible price. Next, identify where human judgment introduces bias: liking managers, extrapolating recent results, trusting forecasts, or trading to relieve discomfort. Convert each vulnerable judgment into a structured assessment, checklist, minimum standard, or exclusion rule. Apply the same definitions across analysts, sectors, and regions so conclusions become comparable. Leaders then enforce the rules and deliberately reduce the freedom to override them, even when experienced practitioners resist. Historical facts and objective metrics anchor the process, while genuinely forward-looking questions remain explicit judgments rather than disguised certainties. Finally, review outcomes and improve the methodology without casually changing the philosophy. The output is not perfect prediction; it is more consistent implementation and fewer self-inflicted errors.
Origin
Extracted from Masters in Business, where Simon Hallett explained how behavioral-finance research led Harding Lovner to structure decisions, narrow portfolio-manager autonomy, and enforce consistent rules.
Core principles
- 01Behavior control matters more than possessing unique information
- 02Structured rules outperform unconstrained individual discretion
- 03Objective evidence reduces predictable judgment errors
- 04Consistency across sectors and geographies improves comparability
- 05Knowledge creates an edge only when converted into practice
How to run it
- 1
Separate Philosophy from Method
State the durable beliefs that define the strategy, then distinguish them from the procedures used to implement it. Methods can improve while the core philosophy remains stable.
Pro tip Write the philosophy in a few testable sentences before designing any checklist.
Watch out Changing beliefs whenever performance disappoints creates an incoherent strategy.
- 2
Map Behavioral Failure Points
Identify decisions where intuition, social influence, recency, overconfidence, or action bias can distort judgment. Use past errors to make the map concrete.
Pro tip Ask where different analysts reach inconsistent conclusions from similar evidence.
Watch out Intelligence and experience do not make practitioners immune to bias.
- 3
Convert Beliefs into Rules
Create defined criteria, checklists, thresholds, and exclusion standards for each recurring decision. Specify the evidence required before a company can advance through the process.
Pro tip Make integrity failures exclusionary rather than offsettable by attractive financial metrics.
Watch out A vague checklist merely creates the appearance of discipline.
- 4
Standardize the Evidence
Use objective historical measures wherever they meaningfully inform the decision, while labeling forecasts as uncertain judgments. Apply definitions consistently across sectors and geographies.
Pro tip Combine backward-looking facts with explicitly documented forward-looking assumptions.
Watch out Do not mistake accounting data for perfect truth or forecasts for objective facts.
- 5
Limit Overrides
Reduce individual freedom to bypass the process and require clear documentation for exceptional decisions. Leadership must enforce the agreed rules even when senior practitioners object.
Pro tip Review overrides separately to determine whether they add value over time.
Watch out Unrestricted autonomy allows old habits to re-enter a supposedly structured process.
- 6
Audit and Improve
Compare decisions and outcomes with the process that produced them. Refine weak methods while preserving useful discipline and avoiding hindsight-driven rule changes.
Pro tip Judge both outcome quality and process compliance because luck can obscure either one in the short term.
Watch out A good outcome does not validate a decision that violated the process.
In the wild
Harding Lovner once believed it could recognize good management after meeting executives and liking them. The firm replaced that intuition with cash-flow return analysis, capital-allocation records, governance checklists, integrity standards, and a separate assessment of strategic vision.
→ Management evaluation became more disciplined, comparable, and resistant to personal affinity bias.
As the firm's process became more structured, portfolio managers lost some autonomy. Hallett's leadership role included defining the rules and ensuring that the team followed them despite an industry culture that treats portfolio managers as unconstrained decision-makers.
→ A stable investment philosophy was implemented through a more consistent and objective methodology.
Common mistakes
Treating Rules as an Insult to Expertise
Practitioners often resist constraints because they associate discretion with professional status. Rules should be judged by whether they improve decisions, not whether they flatter decision-makers.
Collecting Data Without Applying It
Knowing about a bias or useful statistic creates no advantage by itself. The insight must alter a repeated decision process.
Overcorrecting into False Precision
Structure reduces inconsistency but cannot make inherently uncertain forecasts exact. Preserve room for documented judgment without restoring unlimited discretion.
Is it for you?
Best for
It is best for investment teams that have a clear philosophy but produce inconsistent decisions because individual discretion remains too broad.
Not ideal for
It is not ideal for strategies whose edge genuinely depends on rapid, unconstrained reactions to unique events.
From the transcript
“What we've learned is that people need to control their behavior, but they find it difficult to do so.”
“I've had to set out the rules and then make sure we stick to them.”
“turning what we know into practice is your key competitive advantage, in my view, is not the knowledge itself.”
From the episode
Simon Hallett on Investing and Soccer (Podcast)
Simon Hallett