Porter's five forces, applied properly

What the model is actually about

Porter's argument is that the average profitability of an industry is determined by its structure, and that structure can be described by five forces. Some industries are structurally profitable and some are structurally not, regardless of how well individual firms are run.

This is a claim about industries, not companies. 'Porter's five forces of Tesco' is a category error that appears in a great many student assignments: the unit of analysis is UK grocery retail, and Tesco's position within it is a separate question.

The practical payoff is that it tells you where the profit is going. If buyer power is overwhelming, margin flows to customers; if supplier power is, it flows upstream. Naming the destination is what makes the analysis useful.

The five forces and what drives each

Each force is strong or weak for structural reasons that can be evidenced. These are the drivers to look for.

Rivalry is the outcome, not the first question

Rivalry is often taught first and is best analysed last, because the other four forces shape it. High entrant threat keeps rivalry hot; strong buyers force firms to compete on price; substitutes cap what everyone can charge.

The diagnostic questions for rivalry are concentration, growth and differentiation. A concentrated industry with growth and differentiated products can sustain high margins; a fragmented, flat, commodity industry cannot.

Exit barriers deserve more attention than they usually get. An industry where failing firms cannot leave — because assets are specialised, or redundancy costs are high, or a government will not permit closure — stays overcrowded and unprofitable for years.

Entrants: the barrier is what matters

The question is not whether new firms are entering; it is what would stop them. Barriers to entry are structural features that make entry expensive, slow or risky, and they are the reason profitable industries stay profitable.

Economies of scale, capital requirements, regulatory licensing, network effects, brand loyalty, access to distribution and proprietary technology are the classic barriers. Each can be evidenced with an actual number: minimum efficient scale, licensing cost, time to obtain approval.

Note that incumbent retaliation is a barrier too. An industry where incumbents have historically cut prices aggressively against entrants deters entry regardless of the formal barriers.

Digital industries have inverted several of these. Low capital requirements make entry easy, and network effects make it nearly pointless — which is a specific and interesting structural story rather than 'the threat is moderate'.

Substitutes are not competitors

A substitute meets the same customer need with a different product. For rail travel, the substitute is not another train operator — it is driving, flying, or a video call replacing the trip entirely.

This is the force students most often analyse wrongly, by listing competitors. The test is whether the alternative is inside or outside the industry boundary you defined.

Substitutes cap prices. If a substitute exists at a price customers find acceptable, the industry cannot charge above that ceiling however concentrated it is. That ceiling is often the most important single fact in a five forces analysis.

Watch the trajectory. A substitute whose price-performance is improving quickly is a bigger threat than one that is already cheaper but static.

Buyer and supplier power are the same analysis

Both are about relative concentration and relative dependence. Ask who has more alternatives. A supplier with one customer has no power; a customer buying 40% of an industry's output has a great deal.

Switching costs are the other half. A buyer locked into a platform, a certification, or a data format has less power than their volume suggests, and quantifying that lock-in is where the analysis gets interesting.

Threat of integration works both ways and is frequently decisive. A supermarket that could produce its own private-label version of a supplier's product holds power over that supplier even if it never does it.

Do not confuse a large customer with a powerful one. A large customer with many alternative suppliers is powerful; a large customer with one qualified supplier is not.

Defining the industry is the hardest step

Every force depends on where you draw the boundary, and the boundary is a judgement you must state and defend. Is the industry 'coffee', 'coffee shops', 'UK branded coffee shop chains', or 'out-of-home caffeine'?

Draw it too wide and every force is moderate and the analysis says nothing. Too narrow and everything looks like a substitute.

The useful test: include the firms whose pricing decisions materially affect each other. If a change in one firm's price would move another firm's volume, they are in the same industry.

Say the boundary in one sentence at the top of the analysis, with a reason. Markers reward this because it is the step that requires judgement.

Reaching a conclusion

Rate each force as strong, moderate or weak, with evidence, then answer the question the model exists to answer: is this industry structurally attractive, and which force is the binding constraint?

The binding constraint is the one that most limits profitability. Naming it is the analytical move — 'the industry is unattractive primarily because buyer concentration allows the four supermarkets to extract most of the margin' is a conclusion; 'all five forces are moderate to high' is not.

Then say what follows. For an incumbent, the strategy is to weaken the binding force — differentiate to reduce buyer power, build switching costs, integrate. For a potential entrant, the question is whether it can enter in a position where that force bites less.

Where the analysis is part of a larger report, this conclusion feeds directly into the external half of a SWOT and into whatever recommendation you make.

The model's limits, and how to handle them

Five forces was published in 1979 and describes a stable, manufacturing-shaped world. The standard criticisms are that it is static, that it ignores complementors and ecosystems, and that it treats industry boundaries as given.

The usual extension is a sixth force: complementors, products that increase the value of yours. Consoles and games, phones and apps, electric vehicles and charging networks. In platform industries this is often the most important force of all and the original model has no place for it.

Handle the criticism the way you would any limitation: name it, then show your analysis accounts for it. A paragraph on how digitisation has changed entry barriers in your industry is worth more than a generic caveat.

How markers can tell a good one

Five signals, all visible quickly.

• The industry boundary is stated and justified in the first paragraph.
• Each force is rated, with structural evidence and a source rather than an assertion.
• Substitutes are outside the industry, not competitors within it.
• One force is named as the binding constraint.
• The analysis ends with an implication, not a summary of the five ratings.

Using it with other frameworks

Five forces analyses the industry; PESTEL analyses the wider environment that shapes it; the resource-based view analyses the firm within it. Together they answer three different questions and a strong report says which is which.

A common structure for a strategy assignment: PESTEL for context, five forces for industry attractiveness, VRIO or a capability analysis for the firm's position, then SWOT to consolidate and TOWS to generate strategy.

Do not run all four just to demonstrate you know them. Use the ones that answer the question the brief actually asks, and say why you chose them.