Footnote Analysis & Segment Reporting

Step 1: Segment Operating Income Under the Reported (Revenue-Based) Allocation

Corporate overhead of $150.0m is allocated in proportion to each segment's share of the $1,000.0m of total revenue.

Segment Reported Operating Income = Standalone Operating Income − (Revenue Share × $150.0m). For Segment C: $20.0m − (100/1,000 × $150.0m) = $20.0m − $15.0m = $5.0m, a 5.0% (0.05) margin. On this basis, all three segments look profitable, with Segment C the thinnest but still comfortably in the black.

Operating margin is the metric interviewers and analysts use to compare how efficiently each segment converts revenue into profit once shared costs are factored in — it's the number most footnote readers stop at, which is exactly the problem this case is testing.

Step 2: Segment Operating Income Under a Headcount-Based Allocation

The same $150.0m of overhead is now allocated by each segment's share of the 6,000 total headcount instead of by revenue.

Segment Adjusted Operating Income = Standalone Operating Income − (Headcount Share × $150.0m). For Segment C: $20.0m − (3,000/6,000 × $150.0m) = $20.0m − $75.0m = −$55.0m. Because Segment C carries half the company's headcount on only 10% (0.10) of its revenue, a cost driver tied to people rather than revenue lands far more overhead on it — flipping it from a reported $5.0m profit to a $55.0m loss.

This is the core mechanic behind allocation-driven earnings management: the same $150.0m of real cost, split by a different (and arguably more economically sound) key, tells a completely different story about which part of the business is actually carrying its weight.

Step 3: Segment Margin Swing

Margin Swing = Adjusted Operating Margin − Reported Operating Margin. Segment C moves by −60.0 percentage points, by far the largest swing of the three segments. A swing this large concentrated in one segment is the quantitative signal that the reported allocation basis is doing a lot of work to keep that segment looking profitable — precisely the kind of gap an interviewer wants you to isolate before trusting a reported segment margin at face value.

Step 4: What the Additional Footnote Details Confirm

The three footnote details from the setup reinforce, rather than contradict, the concern flagged by the margin swing: a stable segment count rules out a recent re-slicing of segments as the explanation, so the swing is coming from the allocation methodology itself, not a definitional change. A "Corporate/Unallocated" line that has nearly doubled as a share of revenue (8.0% (0.08) to 15.0% (0.15)) shows more cost being kept above the segment lines altogether, which is a separate lever management can use to keep segment-level margins looking stable even as total corporate cost grows. And a related-party customer concentrated in Segment C means even the $100.0m of Segment C revenue used in the allocation itself may not be arm's-length, which would undermine both the revenue-based allocation key and the standalone operating income figure feeding into it.

Final Results

• Segment C reported operating income (revenue-based allocation): $5.0m (5.0% margin)
• Segment C adjusted operating income (headcount-based allocation): −$55.0m (−55.0% margin)
• Margin swing on Segment C: −60.0 percentage points, the largest of the three segments

This kind of allocation sensitivity check is exactly what a buyer's diligence team or an equity analyst runs before relying on segment-level margins in a sum-of-the-parts valuation or a carve-out analysis — a segment that only looks profitable under one allocation key is a segment whose standalone economics need to be re-underwritten from scratch.

Would you like to explore how this same allocation sensitivity would change the answer if Segment C were being valued for a potential divestiture?