Every PMS manager in India faces the same question from clients after a quarterly review: “Why did my portfolio beat (or lag) the NIFTY 50?” Answering with “stock picking” or “market timing” is vague. Brinson-Fachler attribution gives you a precise, quantitative answer.

What is Brinson-Fachler Attribution?

Developed by Gary Brinson, Randolph Hood, and Gilbert Beebower in 1986 (and refined by Brinson and Fachler in 1991), this framework decomposes the difference between your portfolio return and a benchmark return into three effects:

  • Allocation Effect — Did you overweight the right sectors? If you had 30% in IT when the benchmark had 15%, and IT outperformed, your allocation added value.
  • Selection Effect — Did you pick better stocks within each sector? If your IT stocks returned 25% while the benchmark's IT stocks returned 18%, your stock selection within IT added value.
  • Interaction Effect — The combined effect of being overweight in a sector and picking better stocks within it. This captures the synergy (or drag) between allocation and selection decisions.

The Math (Simplified)

For each sector i:

  • Allocation Effect = (Portfolio Weighti − Benchmark Weighti) × (Benchmark Returni − Total Benchmark Return)
  • Selection Effect = Benchmark Weighti × (Portfolio Returni − Benchmark Returni)
  • Interaction Effect = (Portfolio Weighti − Benchmark Weighti) × (Portfolio Returni − Benchmark Returni)

The sum of all three effects across all sectors equals your total active return (portfolio return minus benchmark return), within a small residual.

Why Indian PMS Managers Need This

SEBI requires PMS managers to report performance using Time-Weighted Rate of Return (TWRR). But TWRR tells you what happened, not why. Attribution tells you why.

Consider a real scenario:

Your PMS returned 22% vs. NIFTY 50's 18%. The 4% alpha came from: +2.1% allocation (overweight financials during the rate cut cycle), +1.5% selection (picked HDFC Bank over SBI within financials), and +0.4% interaction.

This level of transparency builds client trust and helps you refine your investment process. It also helps identify when your alpha came from luck (a single stock bet) versus skill (consistent sector allocation).

Common Pitfalls

Sector Classification Matters

The attribution result depends heavily on how you classify stocks into sectors. Using TrueData's corporate classification ensures consistency with how the benchmark index (NIFTY 50) classifies its constituents. Mixing classification systems produces misleading residuals.

Benchmark Selection

Attribution against NIFTY 50 tells a different story than attribution against NIFTY 500. If your PMS holds mid-caps, attributing against NIFTY 50 (large-cap only) will show a permanent allocation effect from size — which isn't really an “active” decision if your mandate is multi-cap.

How to Run Attribution on Capital Advantage

  1. Go to Equity Portfolio and add your holdings with weights
  2. Click the Attribution tab
  3. Select your benchmark (NIFTY 50, NIFTY 500, or SENSEX) and analysis period
  4. View the sector-by-sector breakdown of allocation, selection, and interaction effects

The entire computation runs in seconds. No Excel, no manual sector mapping, no formulas to debug.