The Mechanics — And the Manipulations Built Into Them
EPS is net income divided by the weighted average shares outstanding. The diluted version adds stock options, RSUs, convertible notes, and warrants to the denominator — the more conservative and meaningful figure for equity analysis. This is the version sell-side analysts and earnings databases default to when they report 'EPS,' and it's the one you should always use unless you have a specific reason to look at basic EPS.
What the formula obscures is how much management flexibility exists in both the numerator and denominator. Net income reflects accrual accounting, which means revenues recognized before cash is collected, expenses deferred or accelerated, and non-cash items like depreciation and amortization running through the income statement. The denominator is partly a management decision: buybacks reduce shares outstanding, mechanically boosting EPS even if the underlying business generates no more earnings than the year prior. A company that earns $1B and repurchases 10% of its shares can report 11% EPS growth while growing earnings not at all.
The GAAP-to-non-GAAP adjustment game compounds this further. Most large companies now report 'adjusted EPS' that excludes stock-based compensation, restructuring charges, acquisition-related amortization, and other items labeled 'non-recurring.' In reality, many of these are permanent features of operating the business. When a company's adjusted EPS is 30–40% higher than its GAAP EPS on a sustained basis, the adjustment is not correcting a distortion — it is creating one.
Basic EPS = Net Income ÷ Weighted Avg Basic Shares
Diluted EPS = Net Income ÷ (Shares + All Dilutive Securities)