Active Share Dispension
The Formal Definition
A statistical metric that calculates the percentage of equity holdings within an actively managed mutual fund or institutional strategy that completely diverges from the underlying securities and weightings of its designated benchmark index.
Active Share = 0.5 × ∑ |w_{fund, i} - w_{benchmark, i}|
Cole Barrett's Reality Check
The Unvarnished Bottom Line"Active share is our favorite forensic lie detector for active fund managers. If a fund charges you a 1.5% management fee but has an active share of 45%, you are paying luxury prices for a 'closet indexer' that is basically just buying Apple, Microsoft, and Nvidia and pretending to be a genius."
Interactive Simulator: Test the Math
Real-World Example: Scenario Breakdown
Examining the real numbers for: An investor screening a $100,000 active equity mutual fund claiming 'proprietary market-beating stock selection'
| Execution Metric | Forensically Audited True Active Fund | Closet Indexing Large-Cap Mutual Fund |
|---|---|---|
| Fee / Rate | 0.95% management fee | 1.35% management fee |
| Spread / Buffer | Active Share = 88%; high conviction portfolio of 35 non-benchmark mid-cap compounders | Active Share = 38%; holds 480 of the S&P 500 components with tiny 0.1% tracking adjustments |
| Execution / Status | Portfolio holdings show near-zero overlap with the top 10 positions of the S&P 500 | Effectively mirrors the S&P 500 benchmark after internal trading friction |
| Total Cost / Result | Justified fee premium for real non-benchmark active risk | Paid $14,000+ over a decade for passive beta disguised as active management |
How Brokers Weaponize This Term
Never purchase an active mutual fund with an Active Share below 60%. If the active share is under 60%, the manager is statistically incapable of generating enough gross outperformance to overcome their 100+ basis point expense ratio.
Broker Evaluation Matrix
Cole Approves
Vanguard: Pioneered low-cost passive index funds with near-zero active share by design, charging transparent expense ratios as low as 0.03%.
Read Audit →Cole Flags / Avoids
Legacy Bank Advisory Desks: Channels 401(k) and retirement savers into proprietary in-house mutual funds with sub-50% active share and 1.25%+ expense ratios.
View Trap Details →Frequently Asked Questions
What is considered a 'good' Active Share score?
An Active Share above 80% indicates true active stock picking. Between 60% and 80% is moderately active. Below 60% is universally classified by forensic auditors as closet indexing.
Does a high Active Share guarantee outperformance?
No. High active share only guarantees that your returns will look radically different from the benchmark. You have to take active risk to outperform, but bad active picks mean you can underperform just as dramatically.