If there’s one financial concept you absolutely must understand cold before walking into an investment banking interview, it’s free cash flow. Interviewers ask about it constantly, and the questions go well beyond just reciting the formula. You need to understand what FCF actually measures, why it matters, and how to derive it from the financial statements.
I’ll walk you through all of it — including the distinctions that trip up candidates in technical interviews.
What Is Free Cash Flow?
Free cash flow (FCF) measures the actual cash a business generates after accounting for the capital it needs to maintain and grow its operations. It’s essentially the cash left over that could be used to pay back debt, distribute to shareholders, or reinvest in the business.
The reason FCF matters is that accounting earnings (net income) can be heavily distorted by non-cash items, accounting choices, and timing differences. FCF strips most of that away and tells you what cash is actually moving in and out of the business.
In investment banking, FCF is the foundation of the discounted cash flow (DCF) valuation model — one of the core valuation methodologies you’ll use on the job and defend in interviews.
The Two Types of Free Cash Flow
This is where a lot of candidates get confused. There are two main versions of FCF, and they serve different purposes:
1. Unlevered Free Cash Flow (UFCF)
Also called “Free Cash Flow to the Firm” (FCFF), this measures cash flow available to all capital providers — both debt holders and equity holders — before any financing costs.
This is the version used in a standard DCF to value the enterprise (total business value).
UFCF Formula:
UFCF = EBIT x (1 — Tax Rate) + D&A — Changes in Net Working Capital — Capital Expenditures
Or equivalently, starting from EBITDA:
UFCF = EBITDA x (1 — Tax Rate) + D&A x Tax Rate — Changes in NWC — CapEx
Or the most common simplified version you’ll see in practice:
UFCF = NOPAT + D&A — Changes in NWC — CapEx
Where NOPAT = Net Operating Profit After Tax = EBIT x (1 — Tax Rate)
2. Levered Free Cash Flow (LFCF)
Also called “Free Cash Flow to Equity” (FCFE), this measures cash available to equity holders only, after paying interest on debt and making required debt repayments.
LFCF Formula:
LFCF = Net Income + D&A — Changes in NWC — CapEx +/– Net Borrowings
Or: UFCF — Interest Expense x (1 — Tax Rate) — Mandatory Debt Repayment
LFCF is used when you want to value equity directly, or when assessing how much cash a company has available to pay dividends, buy back stock, or reduce debt voluntarily.
Free Cash Flow Step-by-Step: Starting From Net Income
Here’s a more detailed build-up that’s useful for understanding how FCF connects to the income statement and balance sheet:
- Start with Net Income
- Add back Depreciation & Amortization (non-cash expense)
- Add back other non-cash charges (stock-based compensation, amortization of deferred financing costs, etc.)
- Adjust for changes in Net Working Capital
- If NWC increases: subtract (cash use)
- If NWC decreases: add back (cash source)
- Subtract Capital Expenditures (cash spending on PP&E)
- If calculating UFCF, also add back after-tax interest expense (since UFCF is pre-financing)
This gives you levered FCF. To get to unlevered FCF, you start from EBIT rather than net income, so that interest payments are excluded.
Why Do Investment Banks Focus on Unlevered FCF?
When building a DCF in investment banking, we almost always use unlevered FCF — not levered FCF. Here’s why:
Unlevered FCF reflects the cash generated by the business regardless of how it’s financed. This lets us compare companies with different capital structures on an apples-to-apples basis. A company that’s heavily leveraged might show very little levered FCF (because of high interest payments), but its underlying business operations might be generating excellent cash flow.
By using UFCF, we’re valuing the operations themselves. We then discount those cash flows at the Weighted Average Cost of Capital (WACC), which accounts for the blended cost of debt and equity. The result is enterprise value — from which we can subtract net debt to get to equity value.
Using levered FCF would require discounting at the cost of equity and would give equity value directly — a valid approach (called the Equity DCF or Dividend Discount Model), but less commonly used for corporate M&A valuations in IB.
Free Cash Flow vs. EBITDA: What’s the Difference?
Interviewers love this question. EBITDA is often used as a proxy for cash flow, but they’re not the same thing — and knowing the differences matters.
EBITDA ignores:
- Capital expenditures (which can be enormous for asset-heavy businesses)
- Changes in working capital (which can consume or generate significant cash)
- Cash taxes (EBITDA is a pre-tax measure)
For a capital-light software company, EBITDA and FCF might be relatively close. For a capital-intensive manufacturer or utility, EBITDA can massively overstate actual cash generation because of high CapEx requirements.
This is why M&A deals for capital-intensive businesses often trade at lower EV/EBITDA multiples — the market is discounting for the fact that EBITDA isn’t really “free.”
Common Interview Questions on Free Cash Flow
Here are the questions I see most frequently in IB interviews on this topic:
- “Walk me through the free cash flow formula.”
- “What’s the difference between levered and unlevered FCF?”
- “Why do we use unlevered FCF in a DCF instead of net income?”
- “If a company has high EBITDA but low FCF, what might explain that?”
- “What’s the difference between FCF and EBITDA?”
- “If CapEx increases by $100M, how does FCF change? Walk me through the three statements.”
On the CapEx question: if CapEx increases by $100M (assuming it’s a cash purchase):
- Cash flow statement: CapEx increases in investing activities by $100M — cash goes down $100M at close
- Balance sheet: PP&E (asset) up $100M; Cash down $100M — balanced
- Income statement: No immediate effect — the CapEx will depreciate over time, affecting future periods
- FCF impact: FCF decreases by $100M in the current period
FCF Yield: A Quick Valuation Sanity Check
One quick application of FCF that’s useful to know: FCF yield = Levered FCF / Market Capitalization. It tells you how much free cash flow a company generates relative to its market value — similar conceptually to an earnings yield.
A high FCF yield might indicate an undervalued company; a low FCF yield might indicate an expensive one (or one with high growth expectations baked in). It’s a quick gut-check tool analysts use in equity research and M&A analysis.
Practice With Real Numbers
The best way to master FCF is to practice calculating it from actual financial statements. Pull up a 10-K, find the cash flow statement, and work through the FCF build yourself. Compare your number to what analysts have published on Bloomberg or in equity research reports.
For structured practice on this and other technical topics, check out our IB technical cheatsheet. And if you want to see how our students have used these skills to land offers at the best banks, check out our track record.
FCF is tested in virtually every first-round IB interview. Get it down cold — it’s one of the highest-leverage things you can do to prepare.
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