Peter Lynch (b. 1944) ran Fidelity’s Magellan Fund from 1977 to 1990. Over those 13 years, he posted a 29.2% annualized return, growing the fund from $18 million to $14 billion. He’s widely regarded as the most successful mutual fund manager in history.
Lynch’s style differed from Graham’s. Graham hunted for “cheap, lousy companies”; Lynch preferred “fairly priced growth stocks.” To evaluate them, he proposed a simple yet powerful valuation tool—PEG.
PEG = PE (Price-to-Earnings Ratio) ÷ G (Earnings Growth Rate)
Example: a company trades at 20× PE, with expected earnings growth of 20% over the next three years → PEG = 20 / 20 = 1.0.
Lynch’s rule of thumb:
PEG < 1： Valuation may be low relative to growth
PEG = 1 Fairly valued
PEG > 1： Potentially overvalued—proceed with caution
PEG > 2： Valuation may be high relative to growth
The elegance of PEG lies in this: there is no absolute “high” or “low” PE standard.
A company growing at 5% with a 10× PE isn’t cheap (PEG = 2).
A company growing at 30% with a 30× PE isn’t expensive (PEG = 1).
The faster a company grows, the higher a valuation it can justify. That’s the heart of PEG.
Note: PEG is only one reference dimension, not a standalone buy/sell signal.
While PEG is designed for individual stocks, its thinking can extend to indices:
Broad-based indices: The CSI 300’s earnings growth tracks GDP, around 5–8%. A reasonable PE is ~15–20×, implying PEG ~2–3. Broad indices aren’t well-suited for PEG-based entry/exit timing.
Sector indices: Growth varies widely by sector. Healthcare grows ~15–20%; at 30× PE, PEG ~1.5–2, still acceptable. Brokerage stocks are highly cyclical with volatile growth, so PEG has limited (limited usefulness).
Inspiration for valuation-based DCA: PEG aligns with the DCA logic—buy more when valuations (PE) are low, less when high. The difference: PEG adds a growth dimension.
Beyond PEG, a few of Lynch’s most quoted maxims:
-Invest in what you know: Lynch liked spotting opportunities in daily life. If a restaurant is packed or a brand suddenly trends, that might be an investment signal.
-The rock-turning theory: Investing is like turning over rocks—the more you flip (the more companies you research), the better your odds of finding a gem.
-Hold for the long haul: Lynch said, “If you haven’t made money in the stock market after 13 years, it’s not the market’s fault.”Though famous for stock-picking, he stressed time and patience too.
Even though PEG is a stock-picking tool, its core idea—valuation must match growth—can guide your ETF allocation:
1.Use “The Way of DCA” to set your own valuation percentile parameters and observe historical backtest differences.
2.Use “The Art of Grid” to configure your own underlying and parameters, observing historical backtests across scenarios.
3.Verify via backtesting how starting DCA at different valuation levels affects returns.
Disclaimer: This article introduces investment concepts and analytical tools, and does not constitute investment advice. PEG is only a reference metric; investment decisions require comprehensive consideration.