Here is a brief excerpt from an article written by Michael Porter for Harvard Business Review in which he reaffirms, updates, and extends his earlier, classic HBR article, “How Competitive Forces Shape Strategy” (1979). He also addresses common misunderstandings, provides practical guidance for users of the framework, and offers a deeper view of its implications for strategy today.

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Editor’s Note: “How Competitive Forces Shape Strategy” was Michael E. Porter’s first HBR article, and it started a revolution in the strategy field. In subsequent decades, Porter has brought his signature economic rigor to the study of competitive strategy for corporations, regions, nations, and, more recently, health care and philanthropy. “Porter’s five forces” have shaped a generation of academic research and business practice. With prodding and assistance from Harvard Business School Professor Jan Rivkin and longtime colleague Joan Magretta, he wrote this follow-up article in 2008.

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In essence, the job of the strategist is to understand and cope with competition. Often, however, managers define competition too narrowly, as if it occurred only among today’s direct competitors. Yet competition for profits goes beyond established industry rivals to include four other competitive forces as well: customers, suppliers, potential entrants, and substitute products. The extended rivalry that results from all five forces defines an industry’s structure and shapes the nature of competitive interaction within an industry.

As different from one another as industries might appear on the surface, the underlying drivers of profitability are the same. The global auto industry, for instance, appears to have nothing in common with the worldwide market for art masterpieces or the heavily regulated health-care delivery industry in Europe. But to understand industry competition and profitability in each of those three cases, one must analyze the industry’s underlying structure in terms of the five forces. (See the exhibit “The Five Forces That Shape Industry Competition.”)

If the forces are intense, as they are in such industries as airlines, textiles, and hotels, almost no company earns attractive returns on investment. If the forces are benign, as they are in industries such as software, soft drinks, and toiletries, many companies are profitable. Industry structure drives competition and profitability, not whether an industry produces a product or service, is emerging or mature, high tech or low tech, regulated or unregulated. While a myriad of factors can affect industry profitability in the short run—including the weather and the business cycle—industry structure, manifested in the competitive forces, sets industry profitability in the medium and long run. (See the exhibit “Differences in Industry Profitability.”)

Differences in Industry Profitability

Understanding the competitive forces, and their underlying causes, reveals the roots of an industry’s current profitability while providing a framework for anticipating and influencing competition (and profitability) over time. A healthy industry structure should be as much a competitive concern to strategists as their company’s own position. Understanding industry structure is also essential to effective strategic positioning. As we will see, defending against the competitive forces and shaping them in a company’s favor are crucial to strategy.

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Here is a direct link to the complete article.

Michael E. Porter, Professor of Business Administration at the Harvard Business School, is the author of Competitive Strategy, the recipient of the 1979 McKinsey Foundation Award for the best Harvard Business Review article, and a guest columnist for the Wall Street Journal. Porter developed the much praised MBA course on Industry and Competitive Analysis, lectures widely on competitive strategy, and is a strategic consultant to numerous companies in the United States and abroad.