What are gross, operating, net, and EBITDA margins?

Gross margin (gross profit / revenue) measures production efficiency before overhead. Operating margin (EBIT / revenue) measures total business efficiency including SG&A, R&D, and D&A. Net margin (net income / revenue) shows what shareholders keep after interest and taxes. EBITDA margin is operating margin with depreciation and amortization added back. It is the rung bankers add so two companies that own different amounts of equipment can still be compared head to head. Each rung strips away or restores a layer of costs.

Because the first dollars of revenue have to pay for a lot of the fixed costs, like the buildings, the platform, and the teams, and the next dollars mostly do not. New revenue therefore flows through at an incremental margin, which is usually much higher than the average. Take a company reporting a 25% net margin on $100M of revenue: add $50M of revenue at the same cost ratio, hold operating expenses and interest flat, and roughly $32M reaches net income rather than the $12.5M the average implies. Interviewers can use this to test whether you understand that or not.

Picking one is the trap. The real answer is that it depends on what you pay for each, so ask what the two companies trade at before you commit to either. It is really a valuation question wrapped up as a margin question, and margin data on its own cannot get you to an answer.

Operating margin isolates business performance from capital structure decisions. Two identical companies with different debt levels will have the same operating margin but different net margins because interest expense distorts the bottom line. Operating margin shows how well management runs operations regardless of financing choices.

Operating leverage occurs when a company has high fixed costs relative to variable costs. As revenue grows, fixed costs are spread over more units, causing operating margin to expand rapidly. Conversely, when revenue declines, those same fixed costs cause margins to compress sharply. This is why high-fixed-cost businesses see volatile profitability.

EBITDA margin is popular in leveraged transactions because it approximates operating cash flow, since it adds back depreciation and amortization, the paper charges for assets bought in prior years. But it ignores real capital expenditure needs. Asset-heavy businesses can look artificially profitable on EBITDA margin because the assets behind those D&A charges still have to be paid for.