Porter's five forces

Every industry creates value. The gap between what customers are willing to pay and what it costs to make the offering exists because someone, somewhere, built something useful. The industry's profit is whatever slice of that gap its members manage to keep. Everything else in the picture takes a slice away, and there are only five candidates, because only five parties can plausibly want a piece:

• Buyers take a slice by pushing the price down toward cost.
• Suppliers take a slice by pushing the input cost up toward the price. A worker demanding a raise is a supplier, and so is a component maker with a patent.
• Substitutes cap the price from outside the industry entirely. A customer's other way of getting the same job done sets a ceiling that no amount of pricing restraint inside the industry can lift.
• Rivalry competes away whatever slice remains among the firms already inside. Usually that happens through price, sometimes through cost-inflating arms races (advertising, service levels, capacity).
• Entry decides the duration of whatever is left after the other four have taken their cuts. If an outsider can walk in and copy the position, today's leftover profit is next year's price war.

Why are there exactly five forces?

Compress it into one line, because you'll use this line to explain the whole framework to a client in under a minute: industry profit = value created − buyer's cut − supplier's cut − substitute's ceiling effect − rivalry burn. Whatever survives that subtraction lasts only as long as entry barriers hold it there. So the answer is five forces and not three or eight. Customers, input providers, outside solutions, today's competitors and tomorrow's competitors are an exhaustive MECE partition of "everyone who might want the money," and nothing else belongs on the list.

Some strategists add a sixth box. It's either "government" or complements, which come from the value net of Brandenburger and Nalebuff. Treat government the way you'd treat any other actor. It works through the five, acting as a barrier-builder, a supplier, a buyer, or a rivalry referee depending on the specific policy. A license requirement is an entry barrier. A price cap is buyer power exercised by proxy, and a subsidy to one player is a rivalry distortion. India will give you constant live practice here: import duties, production-linked-incentive schemes, drug price controls, payment-network interchange caps.

How do you score the forces, and what does the verdict mean?

Carry two habits through everything that follows. First, make every score a number backed by evidence. Score each force on a scale of 1 to 5. A 1 is benign, and the force takes almost nothing. A 3 is moderate. A 5 is severe, and the force takes almost everything worth having. Attach at least two named, checkable pieces of evidence to every score before you write it down. Summed, the five numbers range from 5 to 25 and give you a rough index of the neighborhood's overall temperature. That's useful as a sanity check, but the sum is never the deliverable.

Second, a five-forces verdict describes the average member of the industry, not any one firm. Picture a well-run challenger earning real profits inside a brutal industry, or a lazy incumbent earning mediocre returns inside a blessed one. Both are firm effects, and firm effects belong to the Finance galaxy's moat work. Confusing the industry-level verdict with a firm-level one is the most common analytical slip in this whole field, and the rest of the Core section is built to prevent it.

The five forces, driver by driver

Rivalry: how incumbents fight for the marginal customer

You might expect rivalry to be a head count of competitors. The question it answers is sharper. When a customer is up for grabs, do incumbents fight with price, or with something else, or does nobody really have to fight at all? Whether the fight turns to price has nothing to do with anyone's temperament. Structure decides it, through a short list of drivers. Run through them in order on every engagement:

• Concentration and balance. With many similarly sized rivals, sooner or later someone always breaks ranks on price to grab share. One clear leader holding 40 to 55% share often stabilizes pricing instead. It holds up a price umbrella, because it has the most to lose from starting a war. Measure concentration with CR4, the combined share of the top four players, and HHI, the sum of squared percentage-point shares (HHI = Σ sᵢ²). Both get full treatment in the concentration section, with a worked counterexample.
• Market growth. A fast-growing pie lets everyone expand without stealing from anyone. A flat or shrinking one turns every incremental sale into a share fight, because growth is the only thing that lets rivals avoid looking directly at each other's price.
• Cost structure and perishability. Put high fixed cost and low marginal cost together with a perishable product, and you have the most reliable rivalry accelerant there is. Think of an unsold seat, an unbooked hotel night, a kiln that can't be idled without a costly restart. Once a period is nearly over, any price above marginal cost "helps", and marginal cost is close to zero.
• Differentiation and switching cost. A true commodity with a customer who can switch for free hands the entire fight to price. Real differentiation, or an actual cost to switching, gives every player a reason not to compete on price alone.
• Lumpiness of capacity additions. Some capacity can only be added in large, discrete chunks (a new plant, a fleet order of forty aircraft). It tends to overshoot demand when it arrives, and a period of brutal discounting follows until the market re-absorbs it.
• Exit barriers. These include specialized assets with no other use. Labor or social contracts that make shutting down expensive count too. Then there's the fact the industry likes least. Bankruptcy processes recycle capacity instead of retiring it. An airline that reorganizes keeps flying, and its aircraft return to the market at a lower cost basis under a new balance sheet. High exit barriers mean the losers don't leave. They discount, forever.
• Diversity of rivals' goals and horizons. A state-owned player chasing employment, a founder chasing share at any cost, and a private-equity owner harvesting cash can't tacitly agree on anything, because their definitions of "winning" don't overlap. One rational-seeming player's patience looks, from another's seat, like an invitation to undercut.

On an engagement timeline the evidence comes from somewhere else. An equity analyst has ten years of footnotes to mine. A consulting team starting Monday morning has a week. Capacity-expansion announcements and industry-association data will tell you about lumpiness and growth. A handful of distributor calls asking directly "who discounts, and when" will tell you about concentration and cost structure. Win/loss interviews with the client's own sales team cover switching cost and differentiation. Results or investor-day commentary from the largest rivals cover growth and margin trend. None of this needs a data room. It needs you to have written down already, from the drivers above, what evidence would move your score. You're applying the hypothesis-first habit from the problem-solving work.

Threat of entry: how long a favorable position can be expected to last

Entry asks a practical question: "if the current leaders are earning attractive returns, how quickly and how completely could an outsider reproduce that position?" Whether a new firm could theoretically exist here is beside the point. Here are the drivers, again as a checklist:

• Economies of scale. If unit cost falls meaningfully as volume rises, an entrant must either accept a structural cost disadvantage at small scale or make a very large first-day bet. Either one deters.
• Capital requirements. The sticker price of entry matters less than whether that capital is sunk and can't be redeployed if the bet fails. A rented factory deters far less than a purpose-built one.
• Switching costs facing the customer. The same driver that dampens rivalry also blocks entrants. If customers are contractually, technically, or habitually locked to an incumbent, an entrant has to pay to unlock them, on top of paying to be competitive.
• Access to distribution. If the existing channel (shelf space, dealer network, app-store placement, hospital formulary) is already full of incumbent relationships, an entrant must either buy its way in or build a parallel channel from nothing.
• Proprietary technology, patents, or licenses. A legally or technically protected input or process that cannot be duplicated on any budget.
• Government policy. Licensing regimes, spectrum allocation, import duties, and safety or environmental standards that raise the effective cost of entry, sometimes deliberately, as industrial policy.
• Brand identity and expected retaliation. An entrant has to forecast the industry as incumbents will make it look the instant a serious threat appears. A credible history of aggressive price retaliation is a barrier in itself, independent of any of the structural factors above.

On an engagement, entry analysis asks a slightly different question from the equity-analyst version. The equity analyst asks whether industry ROIC will mean-revert over the next decade. You, as the consultant, ask "if my client makes this move, what does the entry barrier facing them personally look like, and what does the entry barrier facing the next challenger after them look like?" A client asking whether to enter an industry is asking about the barrier from the outside looking in, the mirror image of the barrier an incumbent enjoys looking out.

Threat of substitutes: the ceiling nobody inside the industry controls

A substitute is a different way of getting the same job done. It arrives from an entirely different industry and caps the price, and no amount of in-industry cleverness can lift that cap. A rival selling the same product is something else. Two drivers decide how tight the cap is. The first is the price-performance trade-off. How much worse, or better, is the substitute once you adjust for its price? The second is the buyer's propensity to switch, which comes down to habit, awareness, and the switching cost of trying the alternative even once. Ask whether the substitute solves the same underlying job the customer is hiring the product for. Sitting on a different shelf doesn't make something a substitute.

Video-conferencing and business air travel look like they belong to different industries. Both are hired to do the job "have a productive conversation with someone far away". So a good videoconferencing product is a substitute threat to premium business-class fares, and a bad one isn't.

Buyer power: when the customer holds the pen

Buyer power runs on a near-mirror set of the drivers behind supplier power below. Learn the two together, because most learners can name one but forget to check the other:

• Concentration relative to the seller. A handful of large buyers facing many small sellers can extract concessions no fragmented customer base ever could.
• Purchase volume relative to the seller's total revenue. A buyer who represents 20% of a supplier's sales has leverage a buyer representing 0.2% never will, independent of how many buyers exist in total.
• Product differentiation and switching cost. An undifferentiated product with no cost to switch supplier hands the buyer nearly all the power. Real differentiation or an actual switching cost claws it back.
• Buyer information. A well-informed, price-comparing buyer exerts more pressure than one who can't easily benchmark the deal. With transparent online pricing, that informed buyer is increasingly the default.
• Credible threat of backward integration. A buyer who could plausibly start making the input itself extracts better terms from the current supplier even without ever integrating. The threat alone is the leverage.
• Price sensitivity versus total-cost sensitivity. A buyer for whom this purchase is a large share of their own cost base fights harder over price than one for whom it is a rounding error, everything else equal.

Supplier power: the mirror image, run in the other direction

Flip every driver above and point it upstream: supplier concentration relative to the buyer, the supplier's dependence on this buyer's volume as a share of its own revenue, the differentiation of what the supplier provides, and the buyer's cost of switching suppliers. Then add the supplier's credible threat of forward integration. A component maker that could plausibly start selling finished goods directly extracts better terms from its current customers even before it does so. A labor union is a supplier of labor, and you analyze it with this same lens. The same goes for a semiconductor foundry, a raw-material co-operative, or a payments network deciding interchange fees.