Is a PE of 20 Expensive?
This might be the most frequently asked question by beginners. The answer is: it depends on what company you're looking at.
A PE of 20 for a bank stock might be extremely expensive. But a PE of 20 for a fast-growing tech company might be incredibly cheap. Understanding this distinction is the first step toward mastering valuation.
PE Ratio: How Many Years to Earn Back Your Investment?
PE = Stock Price ÷ Earnings Per Share. A PE of 20 means: at current earnings, it takes 20 years to earn back your investment. Think of it as the 'payback period.'
"PE is just a snapshot value. What matters is the company's future earnings, not its past earnings."
| Company | PE Ratio | Meaning |
|---|---|---|
| Bank of China | ~5x | Market expects low/no growth |
| Moutai | ~30x | Market expects stable long-term growth |
| Tesla | ~60x | Market expects explosive future growth |
| A loss-making startup | N/A | No earnings = PE is meaningless |
PB Ratio: What's the 'Liquidation Value'?
PB = Stock Price ÷ Book Value Per Share. A PB of 1 means the market values the company at exactly its net assets. Below 1 means the market thinks the company is worth less than its parts.
PB is most useful for asset-heavy industries (banks, real estate, mining). For tech companies, PB is often meaningless because their real value is in intangible assets — brand, technology, and talent.
PEG: The Growth-Adjusted PE
PEG = PE ÷ Annual Earnings Growth Rate. Peter Lynch popularized this metric. The idea: a company growing at 30% with a PE of 30 (PEG=1) is fairly valued. Growing at 30% with a PE of 15 (PEG=0.5) is a bargain.
💡 PEG Quick Reference
- PEG < 0.5 → Potentially undervalued (if growth is sustainable)
- PEG ≈ 1.0 → Fairly valued
- PEG > 2.0 → Potentially overvalued (market is too optimistic)
- PEG only works for companies with stable, predictable growth
- Cyclical companies (steel, airlines) should NOT use PEG
💡 Valuation Metrics Summary
- PE tells you the payback period — but future earnings matter more than past
- PB measures liquidation value — most useful for asset-heavy industries
- PEG adjusts PE for growth — a PE of 50 with 50% growth rate is fair
- No single metric tells the whole story — use them together
- Duan Yongping: 'I don't look at PE in isolation. I look at the business.'
PE（市盈率）：最常用也最容易被误用
市盈率 = 股价 ÷ 每股收益。它回答的问题很简单：如果公司的盈利水平维持不变，你需要多少年才能回本？PE 20倍 = 你投的钱需要20年的利润才能赚回来。
"市盈率是一个时刻的值，不能简单看。你得知道分母（利润）是可持续的还是一次性的。"
| 公司 | PE | 看起来 | 实际上 |
|---|---|---|---|
| 银行A | 5x | 超便宜 | 可能有坏账隐患 |
| 茅台 | 25x | 正常偏贵 | 利润极其稳定，增速~15% |
| 特斯拉 | 60x | 很贵 | 如果增长率50%+则可能合理 |
| 亚马逊（2015） | 900x | 疯狂 | 利润被刻意压低用于投入，FCF很好 |
💡 使用PE的正确姿势
- 低PE ≠ 便宜——可能是公司在走下坡路（价值陷阱）
- 高PE ≠ 贵——高增长公司的PE天然偏高
- 要用「正常化利润」而非单年利润来计算PE
- 同行业对比PE才有意义——拿茅台和银行比PE没有意义
- 周期性行业的PE在利润最高时最低——这往往是最危险的时候
PB（市净率）：看家底
市净率 = 股价 ÷ 每股净资产。它回答的是：你花1块钱能买到多少「净资产」。PB < 1 意味着你花的钱比公司的清算价值还低——理论上你买下来直接拆了卖零件都能赚钱。
PB适合资产密集型行业（银行、地产、钢铁），不适合轻资产公司（互联网、咨询）。苹果的PB常年在40-50倍——因为它的价值在品牌和生态系统，不在有形资产。
PEG：彼得·林奇的魔法数字
PEG = PE ÷ 利润增长率（%）。彼得·林奇认为PEG是比PE更好的指标，因为它把增长考虑了进去。
例如：一只股票PE 30倍，利润增长率30%，PEG = 1 → 合理。另一只PE 15倍，增长率5%，PEG = 3 → 看起来PE很低，其实偏贵！
实战对比表
| 公司 | PE | PB | 增速 | PEG | 适合的估值方法 |
|---|---|---|---|---|---|
| 贵州茅台 | 25x | 8x | ~15% | 1.7 | PE（利润稳定） |
| 工商银行 | 5x | 0.5x | ~3% | 1.7 | PB（资产密集） |
| 苹果 | 32x | 48x | ~10% | 3.2 | DCF / PE |
| 英伟达 | 45x | 35x | ~50% | 0.9 | PEG（高增长） |
| 宁德时代 | 20x | 4x | ~25% | 0.8 | PEG / PE |
| 中国平安 | 8x | 0.9x | ~5% | 1.6 | PB（保险） |
💡 估值比率速查总结
- PE → 最适合利润稳定的消费品、公用事业公司
- PB → 最适合银行、保险、地产等资产密集型行业
- PEG → 最适合高增长公司（互联网、科技、新能源）
- 没有单一指标能告诉你全部真相——至少用两个交叉验证
- 所有比率都是「此刻的照片」——要结合趋势和行业环境理解