SaaS Growth Case Interview: Cloud Capacity
| Case type | Growth |
|---|---|
| Industry | Technology / Cloud Infrastructure |
| Difficulty | Hard |
| Firm style | BCG |
The case prompt
Our client, NimbusCloud, is the largest US cloud infrastructure provider with 230 petabytes of capacity at the lowest annual cost of $27M per PB. They can build a new data center to increase capacity to 360 PB for $3B. Total market demand is 980 PB. The board requires payback under 5 years. Should they expand?
NimbusCloud is a leading cloud infrastructure company that sells compute and storage capacity to enterprise customers across the US. They are evaluating a major capacity expansion that would increase their footprint by over 50%. The board requires a payback period of less than 5 years for major investments. We need to evaluate whether the economics support this expansion, considering competitive dynamics.
The exhibits
Exhibit 1
US Cloud Infrastructure Cost Curve ($M per PB)
Industry cost curve: annual cost per PB by cumulative capacity, providers ranked low to high cost; NimbusCloud spans 0-230 PB, Competitor B 230-420 PB. Market demand is ~980 PB/year.
Show the data behind Exhibit 1
| Cumulative Capacity (PB) | Annual Cost per PB ($M) |
|---|---|
| 0 (NimbusCloud start) | $20 |
| 230 (NimbusCloud end / Competitor B start) | $27 |
| 420 (Competitor B end) | $32 |
| 600 | $38 |
| 770 | $47 |
| 850 | $50 |
| 900 | $55 |
| 980 (Total Demand) | $60 |
| 1100 | $72 |
| 1200 | $85 |
Exhibit 2
| Parameter | Value |
|---|---|
| Current capacity | 230 PB |
| New capacity after expansion | 360 PB (130 PB additional) |
| Annual cost per PB for new capacity | $27M (same as existing) |
| Upfront investment | $3 Billion |
| Board payback requirement | Less than 5 years |
| Market demand | 980 PB (flat) |
| Competitor B capacity | 190 PB |
Exhibit 3
| Scenario | NimbusCloud | Competitor B | NimbusCloud Delta Profit |
|---|---|---|---|
| Neither expands | No change | No change | $0 |
| Only NimbusCloud expands (+130 PB) | 360 PB total | 190 PB | +$690M/yr |
| Only Competitor B expands (+80 PB) | 230 PB | 270 PB | -$1,150M/yr |
| Both expand | 360 PB | 270 PB | -$390M/yr |
BCGGrowth · hard
Cloud Computing Capacity Expansion
Technology / Cloud Infrastructure
How a strong candidate structures it
A strong framework would analyze
Question by question
- 1
Case context
Understand the Case
“Can you summarize the situation and what the client needs help with?”
- 2
Clarifying
Clarifying Questions
“What questions would you like to ask before structuring your analysis?”
- 3Drill the structure
Structure
Framework
“How would you structure your analysis of this capacity expansion decision?”
- 4Drill the brainstorming
Analysis
Market Analysis
“Exhibit 1 shows an industry cost curve: each provider is ranked from lowest to highest operating cost. In this market, the price is set by the most expensive provider needed to meet total demand of 980 PB. Find the cost of the provider at the 980 PB point — that is today's market price. Now, if NimbusCloud adds 130 PB of low-cost capacity, the most expensive 130 PB of current providers get displaced. What is the new price, and how much does it drop?”
- 5Drill the math
Math
Profit Comparison
“Look at Exhibit 2 which shows the expansion details. Using the market prices you just identified ($60M/PB currently, $50M/PB after expansion) and NimbusCloud's operating cost of $27M/PB, calculate the current annual profit and the new annual profit after expansion.”
- 6Drill the math
Math
Payback Period
“The expansion generates an incremental $690M per year in profit and requires $3B in upfront investment. What is the payback period, and does it meet the board's 5-year requirement?”
- 7Drill the brainstorming
Analysis
Competitive Response
“What if Competitor B reacts? They could also expand by 80 PB. Looking at Exhibit 3, walk me through the game theory of this decision. What should NimbusCloud do?”
- 8Drill the brainstorming
Analysis
Strategic Implications
“What are the broader strategic implications of this expansion beyond the financial analysis?”
- 9Drill the synthesis
Synthesis
Board Presentation
“The board is ready for your recommendation. Please present your findings and recommendation on whether NimbusCloud should proceed with the expansion.”
The worked path
The numbers that decide it
- Current equilibrium price is $60M/PB/year (where demand of 980 PB meets the cost curve)
- NimbusCloud's current annual profit: 230 PB × ($60M-$27M) = $7,590M per year
- Adding 130 PB shifts 130 PB of high-cost supply out, new equilibrium at 850 PB mark = $50M/PB/year
- New profit after expansion: 360 PB × ($50M-$27M) = $8,280M per year
- Delta profit = $690M/year; Payback = $3B / $690M = ~4.3 years (under 5-year threshold)
- Competitor B loses $10M/PB margin ($60M→$50M), totaling ~$1.9B/year loss - strong incentive to react
- If both expand, price drops to ~$47M/PB/year (770 PB mark); NimbusCloud profit = 360×($47M-$27M) = $7,200M, which is $390M LESS than status quo
- Game theory shows NimbusCloud should expand regardless of what Competitor B does (dominant strategy)
- If NimbusCloud doesn't expand but B does, price drops to $55M/PB (900 PB mark); NimbusCloud loses $1,150M/year
Analysis Flow
- 1
Determine current equilibrium price from cost curve
- Demand = 980 PB intersects cost curve at $60M/PB/year
- Adding 130 PB pushes high-cost providers out
- New equilibrium: demand still 980 PB, but last 130 PB pushed right → new price at 850 PB mark = $50M/PB
- 2
Calculate current vs new profit
Current profit = 230 PB × ($60M-$27M) = $7,590M/year
New profit = 360 × ($50M-$27M) = $8,280M/year
Delta: +$690M/year
- 3
Calculate payback period
- Payback: $3B / $690M = 4.3 years (passes 5-year test)
- 4
Analyze competitive reaction
- Competitor B loses $10M/PB × 190 PB = $1,900M/year from price drop
- B has strong incentive to respond
If B also expands (+80 PB): price drops to $47M/PB (at 980-130-80 = 770 PB mark)
Both expand scenario: NimbusCloud profit = 360 × ($47M-$27M) = $7,200M → loss of $390M vs status quo
- 5
Game theory matrix
- Expand/Don't Expand for each player
- NimbusCloud: Expand dominates (better outcome regardless of B's choice)
- If B expands and we don't: lose $1,150M. If B expands and we do: lose only $390M
- If B doesn't expand and we do: gain $690M. If neither expands: $0
Recommendation
Expand. It is the dominant strategy. Base case payback is 4.3 years. Even if competitor reacts, expanding minimizes downside.
Risks
- Demand could shift (new technologies, market contraction)
- Multiple competitors could expand simultaneously
- Construction delays could increase costs
Next Steps
- Move quickly to secure first-mover advantage
- Monitor competitor activity for early expansion signals
- Stress-test assumptions on demand stability
BCGGrowth · hard
Cloud Computing Capacity Expansion
Technology / Cloud Infrastructure
Why this case
This is not a generic growth case about adding customers. It tests a supply-constrained SaaS business where expansion changes the market-clearing price and invites a competitor response. The trap is valuing the 130 PB of new capacity at today’s price without repricing the market. You must combine payback math with game theory and recognize expansion as the dominant strategy.
FAQ
- How do you calculate the payback?
- First compare annual profit before and after expansion. The case moves profit from $7,590M to $8,280M, an incremental $690M per year. Divide the $3B upfront investment by $690M to get approximately 4.3 years. That clears the board’s requirement of less than 5 years, before considering downside scenarios.
- Why does adding capacity lower price?
- Price is set by the highest-cost capacity needed to meet flat demand of 980 PB. Adding 130 PB of low-cost supply displaces the highest-cost 130 PB, shifting the price point from the 980 PB mark to the 850 PB mark. The market price therefore falls from $60M to $50M per PB per year.
- What if Competitor B expands too?
- If both providers expand, the case models NimbusCloud profit at $7,200M, which is $390M below status quo. That is worse than the base case, but better than not expanding while Competitor B adds capacity: that scenario costs NimbusCloud $1,150M annually. Expansion therefore protects the strategic position even under retaliation.
- What is the recommendation?
- Expand, because expansion dominates across the two-player scenarios. If Competitor B does not expand, NimbusCloud gains $690M per year; if B does expand, NimbusCloud loses $390M rather than $1,150M. Proceed with monitoring for demand shifts, construction delays, and additional competitors, and stress-test the flat-demand assumption.
BCGGrowth · hard
Cloud Computing Capacity Expansion
Technology / Cloud Infrastructure