What Works on Wall Street Ch. 2: The Power of Value

"Over the long term, investors buying the cheapest stocks in the market substantially outperform those buying the most expensive." — James O'Shaughnessy

Investment Context

Having shown that human intuition fails, O'Shaughnessy tested individual financial metrics one by one across fifty years to see which genuinely produced excess returns.

The data was clear: buying unloved, cheap companies consistently beat buying exciting, expensive ones over long horizons.

The Wall Street Translation

1. Why Price-to-Sales Won

O'Shaughnessy found the best single metric for identifying winning value stocks was price-to-sales.

The reason is data quality, not theoretical elegance: earnings can be legally reshaped through accounting — depreciation methods, revenue recognition timing, one-off items, reserve provisions — while revenue is far harder to fabricate. Price-to-sales wins because its denominator is harder to manipulate.

It has a clear boundary, though: price-to-sales ignores profitability entirely. A company with enormous revenue and persistent losses can screen very cheap and be worth nothing. O'Shaughnessy therefore never used it alone, which is the origin of the multi-factor model in Chapter 4.

2. The Statistical Cost of High P/E

Buying the highest-P/E glamour stocks ranks among the worst long-run strategies in the data. These companies are priced for perfection, and any earnings shortfall produces a violent decline.

3. What Mean Reversion Actually Requires

Value works through mean reversion: poorly performing companies eventually fix their problems or get acquired and their prices recover, while fast growers eventually saturate their markets, decelerate, and see expensive valuations collapse.

But mean reversion has a precondition that is easy to miss: the business must survive long enough to revert. Companies in permanent decline do not revert; they go to zero. This is exactly why The Little Book of Value Investing Chapter 3 insists on balance sheet checks — cheapness must be accompanied by solvency.

Actionable Trading Rules

1. Use price-to-sales as the first valuation screen: Above 2.0–3.0 generally means paying a premium; below 1.0 warrants further research but is never a buy reason on its own.
2. Be wary of universally popular stocks: When a stock is widely discussed, it is statistically more likely to be fully priced or overpriced.
3. Pair every value metric with a solvency check: On any cheap name, first confirm debt levels and cash flow can carry it until reversion arrives.

Relevance to a Retirement Portfolio

For retirees the practical implication is understanding overall market valuation rather than picking stocks.

When the market's aggregate price-to-sales or price-to-earnings sits at historic highs, expected returns over the following decade are typically lower. That is not a reason to liquidate — timing has a poor historical success rate — but it is a sound basis for adjusting expectations and withdrawal rates. If you planned retirement withdrawals on historical average returns while buying in at well-above-average valuations, your plan may be too optimistic.