ACC 818 — Module 5: Competitive Markets
The textbook model of perfect competition and a contrasting look at monopoly. The source document for this module is structured as two practical Q&A exercises rather than a flowing narrative — recreated below as bullet notes.
Perfect Competition: Defining Characteristics
A perfectly competitive industry has:
- Many small firms (no single firm has market power)
- A homogeneous (identical) product
- Free entry and exit
- Perfect information
- Firms are price takers — they accept the market price; they cannot set it.
Diagnosing Real-World Markets
What’s consistent with perfect competition vs. inconsistent:
| Observation | Consistent? | Why |
|---|---|---|
| Different firms use different production methods | ✅ | Methods can vary; product must be uniform |
| An industry association advertises the product | ✅ | Industry-wide marketing shifts market demand |
| Individual firms advertise their own brand | ❌ | Price takers have no brand to advertise — products are identical |
| 24 firms in the industry | ✅ (potentially) | Many small firms with homogeneous output can fit |
| Top firm has 40%, second 20% of sales | ❌ (probably) | Significant market power; unless MES is very large |
| All firms made large profits last year | ✅ | A demand shock can produce short-run profits before entry erodes them |
Entry Barriers (and How Innovation Bypasses Them)
| Industry | Barrier | How innovation challenges it |
|---|---|---|
| Patented blood pressure drug | Patent | Develop a different chemical with similar effect |
| Legal services | Bar admission, restricted law-school seats | Internet enables routine work by lower-cost lawyers abroad |
| Electricity transmission | Natural monopoly (single grid, huge fixed cost) | Local micro-generation reduces grid dependence |
| Municipal sewage | Natural monopoly | Experimental household-scale natural-pond treatment |
| Social media platform | Network effects (value depends on # of users) | A new platform with the right features can flip dominance |
| First-class mail (Canada Post) | Legal monopoly on first-class only | Email, courier, parcel services compete around the protected core |
| Taxicabs | Restricted municipal licenses | Uber’s app-based model bypassed taxi licensing |
| Hotels | Capital-intensive | Airbnb opened up capacity from existing housing stock |
Key Distinction
- Competitive market ≠ competitive behaviour. A perfectly competitive firm has no rivals to “compete with” — it just accepts the price. Aggressive rivalry is a sign of imperfect competition.
Key Terms
Perfect Competition · Price Taker · Homogeneous Product · Free Entry · Natural Monopoly · Network Effects · Entry Barrier · Minimum Efficient Scale (MES)