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Diluted share count jumps when a company crosses from loss to profit, and it reads as dilution
Claim
The diluted-share denominator is not a continuous series. It switches basis the moment a company crosses from a GAAP net loss to a GAAP net profit, because ASC 260 excludes anti-dilutive securities — and in a loss year, every option and RSU is anti-dilutive.
Diluted shares in a loss year = basic shares. In the following profit year the entire option and RSU overhang lands in the denominator in one step.
So a company that swings to profit shows a large "increase in share count" that is not issuance, not dilution, and not an economic event at all. It is a change of measurement basis.
Evidence — Zillow Group, FY2024 → FY2025
FY2024 was a GAAP loss (−$112M). FY2025 was a GAAP profit (+$23M).
| FY2024 | FY2025 | change | |
|---|---|---|---|
| Diluted weighted-average shares | 234.08M | 254.12M | +8.6% |
| Basic weighted-average shares | 234.08M | ~241.7M | +3.3% |
Read off the diluted line, Zillow looked like it diluted shareholders 8.6% in a single year while spending $670M on buybacks — an alarming combination that invites exactly the wrong conclusion about management.
The 10-Q shows the switch operating in real time, quarter to quarter, in both directions:
| (thousands) | Q2 2026 (loss) | Q2 2025 (profit) |
|---|---|---|
| Basic denominator | 227,896 | 241,083 |
| + Option awards | — | 7,649 |
| + Unvested RSUs | — | 2,933 |
| Diluted denominator | 227,896 | 251,665 |
The truth is the opposite of the diluted series. Basic average shares — which cannot toggle — fell 241,083K → 227,896K, −5.5% yoy, and actual shares outstanding fell −6.7% yoy (241.1M → 224.9M). Zillow was retiring stock aggressively the whole time.
Detection
Two cheap checks, in order:
- Look at the net income sign on both ends of any share-count comparison. If one period is a loss and the other a profit, the diluted series is not comparable. Full stop.
- Cross-check against basic weighted-average, and against actual shares outstanding on the cover page. If diluted rose while basic and the cover page fell, you have found the toggle, not dilution.
The tell is that the diluted increase exactly equals the option + RSU add-back line in the EPS
note, and that line is — on the loss side.
Rule
Use BASIC weighted-average shares for any multi-year share-count trend, and for any per-share CAGR that spans a profit/loss transition. Diluted is the right denominator within a consistently profitable period and the wrong one across a crossover.
State which basis you used. A per-share series that silently switches basis mid-window is worse than one that is simply approximate.
Why this matters more than it looks
This trap fires precisely on the companies where share count matters most to the thesis: turnarounds and just-crossed-to-profitability growth names, where the investor is specifically trying to judge whether growth is being funded by dilution. The measurement artifact points the opposite way from the truth exactly when the question is live.
It also compounds with [[pitfall-yahoo-share-count-dual-class-fpi]] — on Zillow both fired at once, so the vendor share count was wrong and the statement share count was non-comparable.
What would falsify this
Nothing about the accounting — ASC 260 is settled. What would change the practical risk is a vendor publishing a basic-share series alongside diluted by default, which would make the crossover visible without opening the EPS note.
Related
[[pitfall-yahoo-share-count-dual-class-fpi]] · [[pattern-buyback-manufactured-eps-screens-as-growth]] · [[pitfall-divested-segment-corrupts-multiyear-cagr]] · [[principle-primary-source-beats-vendor]]
History
- 2026-08-26 — found in the Zillow analysis. The FY2025 diluted count implied 8.6% dilution against $670M of buybacks; the basic count and the 10-Q cover page both showed the share count falling ~6%. Caught only because the buyback figure and the "dilution" were irreconcilable.