The honest math, in the open.
Anyone can screenshot a whale's gains. We publish the number that matters: the real return on the capital they actually deployed, with realized profit in dollars beside it. Here is exactly how that number is built — and why we'd rather show you a loss than a fantasy.
How whales are identified
A whale is a wallet whose Polymarket activity clears a size and consistency bar over a trailing window — not a one-time lucky ticket. We rank candidates by realized capital deployed and the number of distinct markets traded, then require sustained activity so a single oversized bet can't buy a spot on the leaderboard.
The set is rebuilt on a rolling basis. A wallet that goes quiet ages out; a wallet that keeps trading at size stays in. Identification uses only data available up to the cutoff — never the trades we later score them on. That separation is what makes the performance numbers walk-forward rather than curve-fit.
Where the data comes from
Everything starts on-chain. Positions and fills are read from Polymarket's settlement contracts on Polygon and the public order/trade indexes — the same ledger anyone can audit. We do not rely on a wallet self-reporting its own returns, and we do not ingest a private feed you can't check.
Where the dashboard shows a market price or a resolution, it traces to an on-chain event: a fill at a price, a position opened or closed, a market resolved to an outcome. When a surface is showing illustrative rather than live data, it is labeled Sample data — we never dress sample numbers up as live.
How ROI is computed
We rank whales on the real return on deployed capital: cash PnL plus realized PnL, divided by the cost basis the wallet actually committed. It is read straight from on-chain fills — not a mark-to-mid fantasy and not a number a wallet self-reports.
Beside ROI we show realized profit in dollars, because a percentage alone is misleading: a small stake can post a huge ROI while moving almost no money. Showing both keeps the leaderboard honest about who is actually winning at size.
The numbers, defined
A handful of terms appear across the dashboard. Here is exactly what each one means, so nothing on the board is ambiguous.
Why ROI can be negative — and why we show it
Here is the uncomfortable part. A wallet can sit high on volume and still post a negative real ROI on the capital it deployed. When that happens, we print the negative number in plain sight.
We do this on purpose. A tool that only ever shows green is selling a feeling, not a measurement — and the moment you can't see a loss, you can't trust the wins either. Publishing the losses is what makes the gains falsifiable. The honesty is the product: you get to decide which whales are worth following with eyes open, not a leaderboard engineered to flatter.
Tail the best bettors in the world. If the receipts are red, you see red. That's the point.
What we do not do
TailWhales is intelligence, not a broker and not an advisor. Being explicit about the boundaries is part of being trustworthy.