National Grid Plc ADR (NGG) is overvalued and Southern Company (SO) is slightly undervalued.
Against our estimates of intrinsic value, SO trades at the wider discount: a margin of safety of +9%, against -21% for NGG.
Values as of the 22 Sept 2026 close.
Discounting its cash flows at 7.3% (average of 3 methods) values the shares at $63.55; the price of $76.86 is 21% above that value, and 82% of that value comes from beyond year five.
Leak Score 14/100 on 3 of 12 signals
Discounting its cash flows at 6.8% (average of 2 methods) values the shares at $93.38; the price of $85.15 is 9% below that value.
Leak Score 37/100 on 10 of 12 signals
| Metric | NGG | SO |
|---|---|---|
| Verdict | Overvalued | Slightly undervalued |
| Price | $76.86 | $85.15 |
| Intrinsic value | $63.55 | $93.38 |
| Margin of safety | -21% | +9% |
| Leak Score | 14/100 (3/12) | 37/100 (10/12) |
| Market cap | $77.3B | $98.0B |
| Revenue growth, 5 years | 5.8% | 7.9% |
| Operating margin | 28.5% | 24.2% |
| Net margin | 18.3% | 15.4% |
| Return on equity | 8.6% | 12.7% |
| Debt to equity | 1.19 | 1.95 |
| P/E | 17.6x | 20.6x |
| Forward P/E | 11.7x | 17.3x |
| P/B | 1.5x | 2.5x |
| Dividend yield | 4.3% | 3.6% |