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Profitability ratios

A company can report growing earnings while destroying shareholder wealth. It can shrink margins while increasing return on equity. It can generate cash while GAAP profit tumbles. These paradoxes happen because accounting profit and economic profit are not the same thing, and because a dollar in absolute profit means nothing without context. Profitability ratios bridge the gap—they measure not whether a company is making money, but whether it is making more money than the capital invested in it requires, and whether that profitability is real or an accounting mirage.

This distinction is profound and often overlooked. Return on equity (ROE) answers this question: For every dollar of shareholder capital in the business, how much profit does the company generate annually? A business returning 25 percent annually on equity is creating wealth; one returning 5 percent is destroying it, no matter what its absolute profit figure claims. The distinction matters because capital is not free. If a company invests 100 million dollars of shareholder capital and generates 5 million dollars in annual profit, it is destroying value—shareholders could have invested that capital elsewhere in a savings account or index fund at higher returns. Return on invested capital (ROIC) widens the lens to include both debt and equity capital, giving a clearer picture of how efficiently the business deploys all capital sources and whether management is allocating capital wisely. Profit margins—gross (revenue minus cost of goods sold), operating (after operating expenses), and net (the bottom line)—show what percentage of each revenue dollar survives the journey through the income statement. Together, these ratios reveal whether the business is actually as profitable as the income statement suggests.

Many investors stop here and buy "profitable" companies without asking a second question: Is this profitability sustainable? A high profitability ratio can mean the company has a durable competitive moat—protected by technology, brand, network effects, or switching costs—or it can mean the market is paying a temporary premium that will evaporate as competition arrives and margin pressures increase. This chapter teaches you not just how to calculate these ratios, but how to interpret them: how to distinguish one-time spikes from structural improvements, how to compare profitability across industries where absolute margins vary widely by industry structure, and how to use profitability trends to forecast whether a business is improving or deteriorating.

Sustainable versus unsustainable profitability​

High returns on capital are wonderful, but only if they can persist. A company generating 30 percent ROIC might be earning temporary super-profits that competition will erode away. Or it might have structural advantages that allow those returns to persist for decades. The difference is the presence or absence of barriers to entry and competitive moats. This chapter teaches you to distinguish between the two by examining the historical stability of returns, competitive dynamics, and whether returns are increasing or declining.

Margin expansion and contraction​

Improving margins suggest a business is gaining pricing power, scaling more efficiently, or benefiting from operational improvements. Declining margins suggest competitive pressure, rising input costs, or deteriorating competitive position. Understanding the source of margin changes—whether they are structural improvements that will persist or cyclical changes that will reverse—is crucial to valuation. This chapter teaches you to dig into the income statement to understand what is driving margin trends.

Articles in this chapter​