Each of these appears in your screener columns. Each has a formula, a use, and a way it
misleads — and the third one is the part usually left out.
P/E Ratio
price ÷ earnings per share
How many years of current profit you are paying for. The most quoted valuation metric there is.
The trap: a low P/E usually means the market expects earnings to fall, not that the stock is cheap. Cheap and falling look identical on a screener.
PEG Ratio
P/E ÷ earnings growth rate
P/E adjusted for how fast earnings are growing. Below 1 is the conventional "reasonable" marker.
The trap: entirely dependent on a growth forecast, and forecasts are wrong. Garbage in, confident-looking number out.
Gross Margin
(revenue − cost of goods) ÷ revenue
What is left after making the product. The cleanest single read on pricing power.
The trap: only comparable within an industry. A supermarket at 25% may be excellent; software at 25% is in trouble.
Operating Margin
operating income ÷ revenue
What survives running the whole business. Harder to flatter than gross margin.
The trap: a company can lift it by cutting research and marketing — which improves this year and damages the next three.
Debt-to-Equity
total debt ÷ shareholder equity
How much of the business is borrowed. The main determinant of whether a bad year is survivable.
The trap: the right level varies enormously by sector. Utilities and banks run high by design; that is not a red flag there.
Current Ratio
current assets ÷ current liabilities
Can it cover the next twelve months from what it already holds? Below 1 deserves a look.
The trap: a high ratio can mean unsold inventory or uncollected invoices, which is not the same as strength.
Return on Equity
net income ÷ shareholder equity
How efficiently the company turns shareholders' money into profit. Consistency matters more than the level.
The trap: borrowing shrinks equity, which inflates ROE. A rising ROE with rising debt is leverage, not skill.
Free Cash Flow
operating cash flow − capital spending
Cash left after keeping the lights on. What actually funds dividends, buybacks and debt repayment.
The trap: can be boosted for a year by deferring necessary maintenance. Read it over three years, never one.
Payout Ratio
dividends ÷ net income
The share of profit being handed out. The best single check on whether a dividend is safe.
The trap: consistently above ~80% for a non-utility leaves no room for a bad year. That is when dividends get cut.
Go deeper
Stages 2 and 3 of Fundamental Analysis work
through real statements line by line — where each of these numbers comes from,
which ones management has latitude over, and how the three statements connect to each
other. That connection is the part almost nobody teaches and the part that makes the
rest make sense.