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The Information Ratio measures how much excess return you’re generating per unit of risk taken relative to a benchmark. It tells you how efficiently a strategy or manager beats their benchmark.

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Beginner

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What It Means

The Information Ratio shows how consistently you outperform your benchmark, adjusted for the extra risk you’re taking. High IR = consistent, efficient outperformance. Low IR = erratic or inefficient active management.

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Portfolio Example

  • Your portfolio returns 14% vs. S&P 500’s 10% (4% excess return)
  • Your tracking error (active risk) is 5%
  • Information Ratio = 4% / 5% = 0.80
This means for every 1% of additional risk taken relative to the S&P 500, you’re generating 0.80% of excess return.

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Why It Matters

It separates skilled active management from luck. A high Information Ratio means consistent outperformance, not just occasional big wins. It’s the key metric for evaluating whether active management fees are worth paying.

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Advanced

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Mathematical Definition

Information Ratio (IR) = (Rp - Rb) / TE

Where:
- Rp = Portfolio return
- Rb = Benchmark return
- TE = Tracking Error = σ(Rp - Rb)

Tracking Error = Standard deviation of (Portfolio - Benchmark) returns

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Interpretation Benchmarks

For active equity managers (annualized):
Information RatioInterpretation
< 0Destroying value relative to benchmark
0 to 0.3Weak active management
0.3 to 0.5Moderate (median for active equity managers)
0.5 to 0.75Good (top quartile)
0.75 to 1.0Very good (top decile)
> 1.0Excellent (rare when sustained over 3+ years)

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Historical Context

The Information Ratio emerged from active portfolio management theory in the 1970s-80s, formalized by Richard Grinold and Ronald Kahn in “Active Portfolio Management” (1994). It became the standard for evaluating active management efficiency.

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What Makes It Useful

  • Active Management Focus: Specifically designed to evaluate active strategies against benchmarks
  • Risk-Adjusted: Accounts for the additional risk taken to generate excess returns
  • Consistency Measure: High IR requires consistent outperformance, not volatile alpha
  • Portfolio Construction: Can use IR to optimally combine multiple active strategies
  • Manager Evaluation: Standard metric for comparing active managers

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Detailed Example

Strategy A:
- Returns 15% vs. benchmark 10% → Alpha = 5%
- Tracking Error = 10%
- Information Ratio = 5% / 10% = 0.50

Strategy B:
- Returns 13% vs. benchmark 10% → Alpha = 3%
- Tracking Error = 3%
- Information Ratio = 3% / 3% = 1.00

Strategy B is better: more efficient alpha generation despite lower absolute alpha

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Data Requirements

RequirementDurationNotes
Minimum36 months (3 years)Initial IR estimate
Preferred60+ months (5 years)Meaningful evaluation
Institutional standard3-5 years track recordBefore considering IR credible
Statistical Significance:
  • IR = 0.5 needs ~6 years to be statistically significant at 95% confidence
  • IR = 1.0 needs ~4 years to be statistically significant
  • IR = 1.5 needs ~3 years to be statistically significant
Annual IR estimates are nearly useless due to noise. IR is extremely volatile over short periods.

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Relationship to Sharpe Ratio

If benchmark is the risk-free rate, Information Ratio equals Sharpe Ratio. For most active strategies: 
Simplified relationship (when active returns uncorrelated with benchmark):
SR_p² ≈ SR_b² + IR²

Important: This is primarily theoretical. In practice, long-only equity
strategies have correlated active returns, so the relationship is more complex.

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The Fundamental Law of Active Management

E(IR) = IC × √BR  (theoretical maximum)

Where:
- IC = Information Coefficient (manager skill, typically 0.03-0.10)
- BR = Breadth (number of independent investment decisions per year)
Critical Caveats:
  • This represents theoretical maximum, not expected outcome
  • Realistic IC: 0.03-0.10 (not 0.20+ often assumed)
  • Effective BR is much lower than nominal positions due to correlations
  • Real-world frictions reduce achievable IR to 20-50% of theoretical maximum

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Limitations

  • Benchmark Dependency: Only meaningful with appropriate benchmark
  • Assumes Normal Distribution: Like Sharpe Ratio, assumes normally distributed returns
  • Time Period Sensitive: Short periods give noisy estimates
  • Doesn’t Capture Tail Risk: Can miss rare but severe underperformance

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Alternatives

AlternativeDescription
Modified IRUses downside tracking error instead of total tracking error
Appraisal RatioSimilar concept with different statistical properties
t-statistic of AlphaProvides statistical significance of outperformance

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Related Terms

Alpha

The numerator of IR

Sharpe Ratio

Total risk version

Treynor Ratio

Systematic risk version