How it works
Specify the denominator before comparing companies. Trailing P/E uses reported historical earnings; forward P/E uses estimates. Basic and diluted earnings per share can differ. Adjusted earnings can exclude items that remain in reported profit. Mixing these definitions can make two apparently similar multiples measure different things.
The numerator and earnings must refer to compatible share units and currency. Splits, changes in shares outstanding and unusual income items need attention. Historical comparisons also require the earnings information actually available on that date, rather than a later report inserted into an earlier chart observation.
Worked example
Suppose a fictional share costs 60 and annual diluted earnings per share are 3. P/E is 60 / 3 = 20. If earnings fall to 1.50 while price stays 60, P/E becomes 40 without any price rise. If forecast earnings are 4, forward P/E would be 15, but that calculation depends on an estimate, not a completed result.
Interpretation and limits
With losses or earnings close to zero, the ratio becomes misleading or unstable. Cyclical peak earnings can make a company look unusually inexpensive. Different growth, leverage and accounting can justify different multiples. P/E alone neither measures business quality nor establishes fair value.
Chart practice
Read the dated company filing separately, note its publication date, and inspect available closed daily or weekly bars around it. Student Wyckoff Pro provides chart analysis; prices cannot verify earnings, calculate a justified valuation or turn a low P/E into a confirmed entry.
Primary sources
Sources explain the mechanics and limitations; the editorial examples use invented numbers rather than market quotations.
Your next practical step
Continue with analysis of available closed daily, weekly and monthly bars.
Open the first-chart instructions ↗