What it is
Free cash flow (FCF) is the cash a business generates from operations, minus the cash it has to plow back in to keep the lights on. The formula every analyst uses:
FCF = Operating Cash Flow − Capital Expenditures
Operating cash flow comes straight off the cash flow statement — actual cash collected from customers, minus actual cash paid to suppliers and employees. Capital expenditures are also on the cash flow statement, usually under "Investing activities," and represent money spent on long-lived assets (factories, servers, leases, capitalized software).
What FCF deliberately excludes: accounting accruals like depreciation, working-capital swings, mark-to-market gains, and stock-based compensation reversals. That's why FCF tends to lag reported earnings by a quarter or two — and why it's also harder to game. A company can fudge an earnings number; it's much harder to fudge whether cash actually came in.
What "good" looks like
Absolute FCF only matters in context. A few useful anchors:
- FCF yield (FCF ÷ market cap) is the comparable across sizes. A 5% yield at a $50B cap is the same signal as a 5% yield at $500B — the smaller name is just easier to underwrite.
- 5%+ is a B-grade signal for a mature business.
- 8–10%+ is increasingly rare and shouts "the market is mispricing the cash this thing prints."
- Negative FCF isn't always bad. A growth company plowing every dollar into capex (cloud infrastructure, fabs, biotech R&D) can be reasonable — but it puts the burden of proof on the moat and the growth rate.
Why it matters
Three reasons FCF dominates the durability side of our scoring:
- It funds everything optional. Dividends, buybacks, acquisitions, debt paydown — all come out of FCF. A business with zero FCF can do none of those without diluting equity or raising debt.
- It survives multiple compression. Earnings multiples re-rate; cash collected from customers doesn't. The companies that compound through bear markets are the ones whose FCF stays positive when their P/E gets cut in half.
- It's the input to a real DCF. Every discounted cash flow model is built off projected FCFs. A name with no historical FCF to anchor projections forces you to invent the discount-able stream — which is usually a tell that you're investing on narrative.
Common gotchas
- Banks and insurers don't produce meaningful FCF via OCF − CapEx. Their cash flow statements are dominated by loans extended, deposits taken, and policy reserves — items that obscure operating cash flow. For financials we use return on equity and the debt-to-equity ratio as durability proxies instead, and explicitly mark FCF as n/a.
- REITs use FFO (Funds From Operations), not FCF. A REIT's "capex" line includes property acquisitions, which dwarfs everything else — so OCF − CapEx prints as enormously negative on a healthy property company. The Bull Rankings model treats REITs the same way it treats financials.
- Look at the period. Some screeners show last-fiscal-year FCF; others use TTM. A name whose FCF collapsed in Q4 will look healthy on FY data and broken on TTM. We use TTM unless the company hasn't filed enough quarters, in which case we fall back to FY and label it.
- Stock-based comp. Most companies add SBC back to operating cash flow because it's non-cash. But SBC is a real economic cost — it dilutes shareholders. A company with $4B FCF and $3B of annual SBC is closer to $1B of true owner FCF. Our scoring doesn't adjust for this directly, but the ROE signal indirectly catches it (heavy SBC drags ROE through equity-issuance dilution).
Bottom line
FCF is the single most-weighted input to our durability grade. It's the closest thing to "what does this business actually produce" that you can pull from a financial statement. When it's positive and growing, the rest of the analysis is downstream of confirming the moat. When it's negative or shrinking, no amount of growth story makes the math work for long.