Porter's Five Forces

Overview

Some industries earn 30%+ margins decade after decade; others fail to earn their cost of capital despite intelligent, well-funded firms. The cause is industry structure. Porter's 1979 five forces — new entrants, supplier power, buyer power, substitutes, rivalry — determine long-run profitability. A firm's earnings are the residual after those forces have taken their cut. Strategic goal: position where the forces are weakest; where possible, change the forces in your favor through scale, switching costs, differentiation, or vertical integration.

Composes with network-effects, switching-costs, signaling-games, pmf-crossing-the-chasm.

When to Use

• Entering or exiting an industry; strategic planning; explaining why a business is profitable or unprofitable despite good execution; evaluating an investment in a specific sector
• Someone says: "barriers to entry," "buyer/supplier power," "industry attractiveness," "structural competitiveness"
• Sizing a sector reshaped by AI: "who captures the profit in AI?", "does AI capex / compute supplier power make this industry attractive?", "can we win against AI-native competition or open-weight substitutes?"

When NOT to use: dynamic technology disruption; platform/ecosystem markets; very new markets (no stable structure); firm-level analysis (use VRIO instead).

Coaching Novices (Adaptive Front Door)

• Engine mode: concrete industry/decision → run The Process directly.
• Coach mode: unfamiliar or no concrete case → guide step by step.

In Coach mode, respond one step at a time. Each [WAIT] is a hard stop — output only that step's question, then stop.

1. One-liner: some industries are structurally profitable, others hostile — five forces determine which, and a firm's earnings are the residual after those forces take their cut.
2. Check fit: dynamic transitions, platforms, very new markets → point elsewhere.
3. Elicit their real industry. > [WAIT — do not advance until user responds]
4. Walk through each force one at a time; ask user to score and name the binding force. > [WAIT — do not advance until user responds]
5. Close by naming the binding force and the strategic move that shapes it. > [WAIT — do not advance until user responds]

The Process

Run the Five-Forces Analysis. Score each force, identify the binding constraint, design the strategic response.

Step 1 — Define the industry boundary. The right boundary: the set of competitors directly substitutable from the typical buyer's perspective. Test: if a buyer is not considering company X as an alternative, X is in a different industry.

Step 2 — Score each force (1=weak/favorable, 5=strong/hostile).

• New entrants — capital requirements, scale economies, brand loyalty, switching costs, distribution access, IP/licenses, retaliation
• Supplier power — supplier concentration, switching costs, forward-integration threat, input importance
• Buyer power — buyer concentration, purchase volume, product standardization, switching costs, backward-integration threat
• Substitutes — relative price-performance, buyer propensity to switch, outside-industry alternatives
• Rivalry — competitor count, growth rate, fixed costs, differentiation, switching costs, exit barriers

Step 3 — Identify the binding force. The five forces don't average. Name the single most binding force.

Step 4 — Strategic response by binding force.

• Entrants binding → raise barriers (scale, brand, switching costs, IP)
• Supplier power binding → backward integration, multi-source, alternative supply
• Buyer power binding → differentiate, increase switching costs, fragment buyer base
• Substitutes binding → improve price-performance vs substitutes, or pivot value proposition
• Rivalry binding → consolidate (M&A), differentiate, find defensible niche, or exit

Step 5 — Validate against industry profitability data. If predicted and actual ROIC diverge, you missed a force or an enabling factor. Sources: IBISWorld, Damodaran NYU dataset, public company 10-Ks.

Output: Five-Forces Analysis

# Five-Forces Analysis: <industry>
Boundary: <definition> | Substitutable alternatives: <list>
| Force | Score | Key drivers |
|---|---|---|
| New entrants | _ | |
| Supplier power | _ | |
| Buyer power | _ | |
| Substitutes | _ | |
| Rivalry | _ | |
Binding force: <name> — <why>
Strategic response: <specific move>
Validation: predicted ROIC <…> vs actual <…> | gap: <…>

→ Method in Action: Porter's 1979 HBR Paper and Its Empirical Foundation · Porter's US Passenger Airline Analysis → 2026 lens: The AI Foundation-Model Industry Structure (2024–2026)

Pack: Five-Forces by Industry Archetype

Industry	Strongest force	Typical ROIC
US passenger airlines	Rivalry + buyer power	<5%
Pharmaceuticals (branded)	Entry barriers (patents)	15-25%
Enterprise SaaS	Low rivalry + switching costs	20-35%
Restaurants	Rivalry + low entry barriers	5-10%
Search engines	Entry barriers + data moats	>40%

Common Rationalizations

[D] = designed upfront | [O] = observed in real use. [O] entries are more valuable.

Fake move	Reality
[D] "Five-forces is static, ignore it"	Refresh every 2-3 years — don't abandon, refresh.
[D] Averaging the five scores	The strongest force is the binding constraint; averaging hides it.
[D] Industry defined too broadly or too narrowly	Refine until competitors are mutually substitutable from buyers' view.
[D] Ignoring dynamic shifts	Re-run when underlying technology or regulation shifts.
[D] Strategic response spread across all five forces	Focus on the binding force first; the rest are background.
→ Add [O] entries here after each real use — paste the actual failure pattern	What went wrong and why

Red Flags

• Forces scored on intuition without evidence | Binding force not named ("moderately attractive" is not a finding)
• Industry boundary set to flatter own position | Substitutes from outside the industry missed
• Strategic response spread across all five forces equally | Snapshot used as static >3-5 years

Verification

• Boundary defined and tested against buyer substitution behavior
• All 5 forces scored 1-5 with specific drivers
• Single binding force named; strategy targets it specifically
• Validated against actual industry ROIC data
• Dynamic shifts noted (technology, regulation)

→ Primary sources: references/sources.md

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Part of deciqAI Knowledge Skills — 227 open-source thinking skills that make rigor executable for AI agents. The same skills power every deciqAI agent, which runs them autonomously to operate your company. See it run → https://www.deciqai.com/c/porters-five-forces · ⭐ Star the repo → https://github.com/deciqAI/knowledge-skills · Contributions welcome.

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