Sector-Specific Ratios & Metrics
Private bank metrics share the same vocabulary as PSU bank metrics, NIM, GNPA, CASA, ROE, but require fundamentally different interpretation benchmarks, analytical context, and quality assessment standards. A 3.0% NIM at HDFC Bank is structurally inferior to a 3.0% NIM at ICICI Bank, because HDFC Bank's loan mix is more conservative (more home loans, less unsecured) and should earn lower yield. Understanding not just the metric but the business model context that makes the same number mean completely different things at different banks is the distinguishing feature of institutional-grade private bank analysis.
Income Metrics
Net Interest Margin (NIM)
| Bank Category | Poor | Average | Good | Exceptional |
|---|---|---|---|---|
| Large Private (HDFC, ICICI, Kotak) | <3.2% | 3.2-3.8% | 3.8-4.3% | >4.3% |
| Mid Private (Axis, IDFC FIRST) | <3.5% | 3.5-4.2% | 4.2-4.8% | >4.8% |
| Small Finance Banks | <7.0% | 7.0-9.0% | 9.0-11% | >11% |
| PSU Banks (reference) | <2.5% | 2.5-3.0% | 3.0-3.3% | >3.3% |
Private bank NIM decomposition requires understanding: what proportion of NIM comes from sustainable sources (CASA advantage, secured lending spread) versus temporary sources (unsecured lending, treasury gains, one-time recoveries)? A 4.5% NIM driven 60% by unsecured personal loans is more fragile than a 3.8% NIM driven 70% by mortgage and auto loans with CASA-funded cost advantage.
Fee Income Ratio
Fee income as a percentage of total income. This metric does not exist meaningfully in PSU banking but is critical for private banks. ICICI Bank at approximately 1.8% of assets in fee income (versus HDFC Bank at 1.2 to 1.3%) demonstrates a more diversified revenue base that cushions NIM compression during rate cycles.
Cost-to-Income Ratio
Private banks operate at 35 to 45% cost-to-income versus PSU banks at 50 to 60%. This 15 to 20 percentage point efficiency gap represents a structural competitive advantage. Kotak at approximately 35% is best-in-class. IDFC FIRST at approximately 70% (still investing in branch and customer acquisition) is the outlier that will need to demonstrate CIR convergence to justify its valuation.
Asset Quality: Different Standards
Private bank GNPA expectations are fundamentally tighter than PSU banks. A GNPA of 2.5% at a private bank is a serious concern that warrants analyst scrutiny. The same 2.5% at a PSU bank would be considered healthy. This is because private banks have superior underwriting, better collections infrastructure, and a loan mix weighted toward lower-NPA asset classes.
| GNPA Level | Private Bank Assessment | PSU Bank Assessment |
|---|---|---|
| <1.0% | Excellent. Best-in-class underwriting. | Extraordinary. Almost unachievable. |
| 1.0-2.0% | Good. Institutional quality. | Excellent. |
| 2.0-3.0% | Elevated. Needs investigation. | Good. Manageable. |
| 3.0-5.0% | Stressed. Potential crisis. | Acceptable with provisions. |
| >5.0% | Crisis. Yes Bank territory. | Elevated but common historically. |
Slippage Ratio: For private banks, quarterly slippage above 2% of opening standard book is a warning. Above 3% is a crisis signal. Compare this to PSU banks where 3 to 4% slippage was normalised during the 2017 to 2019 period.
Profitability & Valuation
ROA: The Master Metric
| ROA Level | Assessment | Examples |
|---|---|---|
| <1.0% | Below par for private banking | Axis (pre-transformation), IndusInd (current) |
| 1.0-1.5% | Adequate. Meeting minimum threshold. | Federal Bank, IDFC FIRST (target) |
| 1.5-2.0% | Good. Institutional quality. | HDFC Bank, Kotak |
| 2.0-2.5% | Excellent. Best-in-class. | ICICI Bank (current), AU SFB |
| >2.5% | Exceptional (SFBs with high NIM) | Some SFBs in peak cycle |
The ROE-P/B Valuation Framework
The single most important valuation relationship in banking. A bank's justified P/B multiple is mathematically derived from its sustainable ROE, growth rate, and cost of equity.
The Gordon Growth Model applied to banking: Justified P/B = (ROE minus g) divided by (COE minus g), where g is sustainable growth and COE is cost of equity (approximately 12 to 14% for Indian banks).
| Sustained ROE | Justified P/B | Current Reality |
|---|---|---|
| 12-14% | 1.0-1.5x | Best PSU banks (SBI, BoM) |
| 14-17% | 1.5-2.5x | Axis Bank, Federal Bank |
| 17-20% | 2.5-3.5x | ICICI Bank, HDFC Bank |
| 20-24% | 3.5-5.0x | Kotak Mahindra Bank |
| >24% | 5.0x+ | AU SFB at peak (SFB premium) |
When P/B exceeds justified P/B by more than 30%, the market is pricing in ROE improvement that has not yet materialised. When P/B is below justified P/B by more than 20%, the market is pricing in ROE deterioration. Both are investable signals if your analysis of ROE trajectory is correct.