Follow the money and identify who carries the risk
Financial services businesses do more than sell a product at a markup. They may lend money, pool risks, process transactions or manage assets. A recommendation that increases revenue can also increase credit losses, funding needs or exposure to adverse events.
Quick Prep’s financial services preparation builds the habit of analysing growth alongside risk and operating capacity. Start by naming the business model. Then define the balance, transaction or customer activity that generates revenue.
The Bank of England explains the role of banks in payments and lending and the relationship between lending risk and interest charges. This is a useful starting point for understanding why a bank case needs more than a standard retail revenue tree. Bank of England: What do banks do?
Use separate models for distinct businesses
Retail and commercial banking: Interest income comes from earning assets such as loans; funding generates interest expense. Fees can contribute additional revenue. Operating costs and credit losses then affect profitability. Ask how quickly loan and deposit pricing can change, and whether new customers behave like existing ones.
Insurance: Premiums fund claims, operating expenses and other obligations, while investment income is a separate source of earnings. Underwriting analysis requires consistent earned-premium and claims definitions. A low acquisition price is not enough if the new customer group has substantially higher claims.
Payments: Revenue may be linked to transaction value, transaction count or service fees. A processor’s retained revenue is only part of the money moving through its system. Costs can include network fees, fraud losses, customer support and technology.
Wealth and asset management: Fee revenue may depend on average assets under management and fee rates. Changes in assets can come from net customer flows or market movements. Growing asset values are not necessarily evidence of successful customer acquisition.
Metrics and the questions behind them
| Metric | Meaning for case analysis | Interpretation to verify |
|---|---|---|
| Net interest margin | Net interest income / average interest-earning assets | Period, annualisation and asset scope |
| Cost-to-income ratio | Operating expenses / operating income | Which income and expense items are included |
| Credit loss rate | Credit loss expense relative to a defined exposure base | Accounting provision versus realised loss |
| Insurance loss ratio | Incurred claims / earned premiums | Gross or net of reinsurance |
| Combined ratio | Loss ratio plus expense ratio under stated definitions | An underwriting measure, excluding investment returns |
| Payments take rate | Net revenue / processed transaction value | Gross revenue and pass-through fees |
| Net flows | Customer inflows less outflows | Separate from market-driven asset changes |
Capital and liquidity are distinct considerations. Capital supports loss absorption; liquidity concerns meeting cash obligations when due. You do not need to invent regulatory ratios to acknowledge that a proposed lending expansion must satisfy both.
Worked exercise: should a lender pursue faster growth?
Illustrative interview exercise. All figures are fictional and refer to one annual period.
A lender’s average loan balance is 100 million. Loan interest yield is 8%, funding cost is 3% on an assumed equal funding balance, expected credit loss expense is 2% of loans, and operating costs are 1.5 million. Ignore fees and tax.
Interest income is 8 million and funding expense is 3 million. After 2 million of credit losses and 1.5 million of operating costs, the simplified annual profit is 1.5 million.
Management proposes increasing average loans to 120 million. Assume loan yield and funding cost stay unchanged, operating costs rise to 1.8 million, and the loss rate increases to 3% because the expanded portfolio is riskier.
The new calculation is 9.6 million − 3.6 million − 3.6 million − 1.8 million = 0.6 million. Loans grow 20%, but profit falls 60%.
A useful recommendation would explore a more selective customer segment, different pricing or better credit performance before approving broad growth. It would also examine the capital required and the timing of losses. The simplified calculation does not value the portfolio or establish whether lending terms are appropriate for actual borrowers.
Questions that improve the case discussion
In a bank profitability case, ask whether the issue comes from deposit pricing, loan mix, credit quality or servicing costs. A rising policy rate does not imply that every bank’s margin improves; the timing and structure of assets and funding matter.
In a payments case, distinguish higher transaction count from higher transaction value. A change in merchant mix can move revenue and risk in different directions. Estimate fraud and support costs at the level relevant to the decision.
In insurance, test whether growth is coming from underpriced risks, and avoid treating one period’s claims experience as a stable long-term rate. In wealth management, examine fee compression and client retention separately from market performance.
Practise making growth conditional
Build a short profit model for a bank, an insurer and a payments provider. Change one driver in each and explain why its effect differs. Then write a recommendation that specifies the customer segment, the economic threshold and the risk condition required for expansion.
This primer supports interview reasoning rather than personal financial decisions. Continue with Finance Modeling to practise the calculations and Case Interview Mastery to turn the analysis into a clear recommendation.
