Equity Research interview preparation
Sell side and buy side. Every question is either traced to a named firm from a public candidate report, or tagged at desk level when we could not trace it. Answers lead with the point, then the mechanism, then the limitation.
100 questions, mapped to the firms that asked them
- Questions
- 100
- Traced to a firm
- 72
- Firms
- 45
- Updated
- September 2026
037How would you model a subscription software business, and what metrics matter?Insight PartnersSoftware · New York · 2022Piper SandlerInvestment Banking · Burlingame · 2026
Say this
Model the recurring revenue base by cohort rather than the income statement. Opening ARR, plus new, plus expansion, less churn and downgrades, gives closing ARR. Everything else follows from that roll-forward.
Then walk it
- The ARR bridge is the model. Once you have opening ARR, new bookings, expansion and churn, revenue is largely determined, because recognised revenue is a lagging function of the contracted base.
- Key metrics: net revenue retention, gross retention, gross margin, customer acquisition cost payback, and the rule of forty which is growth plus free cash flow margin.
- Net retention above 110 percent is the single most important number, because it means the installed base grows without selling anything new. That is what justifies a high revenue multiple.
- Watch the gap between billings, revenue and deferred revenue. Billings lead revenue, so a slowdown shows up in billings a quarter or two before it hits the reported line. That is often where the variant view lives.
- Cost side: gross margin tells you how much real compute or support sits in cost of revenue, sales and marketing efficiency tells you whether growth is bought or earned, and R&D as a share of revenue tells you about future product.
- And take stock-based compensation seriously, because in software it is large enough to determine whether the company is profitable at all.
Where candidates lose it
Modelling revenue directly and ignoring the ARR bridge and deferred revenue. Also quoting the rule of forty without knowing whether it uses free cash flow margin or operating margin, since the two give very different answers.
Expect next
- What is the rule of forty?
- Why do billings lead revenue?
- What net retention would justify a 10 times revenue multiple?
Reported by candidates at Insight Partners (Software, New York, 2022); Piper Sandler (Investment Banking, Burlingame, 2026). Source: Wall Street Oasis.
038What is the rule of forty, and what are its weaknesses?Technology coverageGrowth equity
Say this
Revenue growth plus profit margin should exceed 40. It says a software company can be forgiven for losing money if it is growing fast, or for growing slowly if it is profitable, but not both.
Then walk it
- The logic is a trade-off: spending on growth suppresses margin, so the combined figure measures whether that spend is productive.
- The first weakness is the margin definition. Free cash flow margin, operating margin and EBITDA margin give very different scores for the same company, and firms naturally quote the flattering one.
- The second is that it treats a growth point and a margin point as equivalent. They are not: for a long-duration asset, a point of durable growth is worth far more than a point of margin, because it compounds.
- The third is that it ignores the quality of the growth. Growth bought through acquisitions, or through discounting that damages net retention, scores the same as organic growth from pricing.
- And it says nothing about durability. A company at 60 today that decelerates sharply next year is worth less than a steady 42.
- So I would use it as a screen to compare companies quickly, never as a valuation input. The valuation question is always durability, and the rule of forty is silent on it.
Where candidates lose it
Quoting the heuristic without a critique. Anyone can state it. Naming the margin-definition problem and the growth-versus-margin asymmetry is what shows you have used it rather than read it.
Expect next
- Which margin would you use?
- Would you rather have 20 percent growth at 20 percent margin, or 40 percent growth at breakeven?
- How do you assess durability of growth?
Firm tags come from public, anonymous candidate reports on Wall Street Oasis: strong signal, not sworn testimony. Firms are named as the places a question was reported, not as partners of Fin Maverick. Answers are written for this page to show how to think out loud; they are not scripts to recite.

