Why A Negative P/E Happens and What to Use Instead

What It Covers

Stephen Morris and Andrew Sather break down why a stock's P/E ratio turns negative, identifying three root causes — real operating losses, one-time accounting charges, and heavy reinvestment spending — then outline four alternative valuation tools investors can use when P/E becomes meaningless for unprofitable companies.

Key Questions Answered

• •Negative P/E Diagnosis: A negative P/E always results from negative earnings, never a negative price. Before rejecting a stock, determine whether the core business operations are losing money or whether a one-time event — such as a write-down, legal settlement, or restructuring charge — temporarily distorted net income without reflecting true ongoing business performance.
• •Trailing vs. Forward P/E: Forward P/E relies on Wall Street analyst estimates, which are highly unreliable. Quantitative and algorithmic traders typically favor trailing P/E for this reason. When evaluating any company, treat forward P/E as a rough directional signal only, and weight trailing P/E or multi-year average earnings more heavily for valuation decisions.
• •One-Time Charge Evaluation Framework: When a company takes a large write-down — as Crocs did after overpaying for Hey Dude — assess whether management is being transparent, whether the core business still generates free cash flow, and whether this represents an isolated mistake or a recurring pattern of poor capital allocation decisions before exiting or holding the position.
• •Price-to-Sales as a Growth Proxy: For companies with negative earnings, price-to-sales serves as a viable alternative valuation metric. James O'Shaughnessy's quantitative research in *What Works on Wall Street*, covering multiple decades of market data, identified price-to-sales as a statistically meaningful predictor of returns across large stock universes, particularly for early-stage or hypergrowth companies.
• •Free Cash Flow Over Net Income: When net income is negative due to accounting noise, free cash flow provides a cleaner picture of business value. Examine operating margin and gross margin to identify whether profitability exists above the net income line, then build valuation estimates using free cash flow projections rather than earnings-based multiples like P/E or DCF.