What is Porter's Five Forces?
Michael Porter's 1979 framework analyzes industry attractiveness — the long-run profit potential of competing in an industry — through five forces. Rivalry among existing competitors rises with industry concentration, slow growth, high fixed costs, undifferentiated products, and high exit barriers. Threat of new entrants falls with high entry barriers (capital, regulation, brand, network effects). Bargaining power of suppliers rises when suppliers are concentrated, switching costs are high, or substitutes are scarce. Bargaining power of buyers rises when buyers are concentrated, products are undifferentiated, or buyers can backward-integrate. Threat of substitutes rises when substitutes have better price-performance or low switching costs. The collective strength of the five forces determines industry profitability.
How Porter's Five Forces actually works
The framework breaks down into the following moving parts. Knowing what each piece is — and what it is not — is what separates a B-grade answer from an A-grade answer in a written assignment.
- Rivalry — concentration, growth rate, fixed costs, differentiation, exit barriers
- New entrants — economies of scale, capital, brand, switching costs, regulation, distribution
- Supplier power — supplier concentration, switching cost, forward-integration threat
- Buyer power — buyer concentration, product standardization, backward-integration threat
- Substitutes — relative price-performance, switching costs, propensity to substitute
- Strong forces = lower industry profit; weak forces = higher industry profit
A worked example: US airlines vs US software
US airlines have brutal Five Forces: high rivalry (overcapacity), high supplier power (Boeing, Airbus duopoly + unionized labor), high buyer power (price-comparison sites), high substitute threat (cars, video conferencing, trains), moderate entry threat (capital is high but recurring entrants exist). Industry ROIC has averaged below cost of capital for decades. US enterprise software has weak forces: low rivalry (network effects create winner-take-most), low buyer power (high switching costs), low supplier power, low substitute threat, low new-entrant threat (incumbents acquire upstarts). Industry ROIC routinely exceeds 30%. The structural difference dwarfs management quality.
Don't lose marks for these
- Treating Five Forces as a SWOT — they are an industry analysis, not a firm analysis
- Listing factors without scoring force strength
- Ignoring complementors (the "sixth force" Brandenburger added)
- Forgetting that forces change over time
How to use this on the exam
Score-maximizing moves
- Score each force High/Medium/Low and justify
- Identify the dominant force for the industry
- Cite Porter 1979 by name
When to use Porter's Five Forces (and when not to)
Use Porter's Five Forces when your assignment asks you to analyze, structure, or recommend — and when you have at least two data points to populate every cell of the framework. Skip it when the question is asking for a numerical answer or a single recommendation, since Porter's Five Forces is a structuring tool, not a calculator.