Arkham Prediction Market Elo: review and alternatives

What it is

A rating on Arkham’s platform that rises with correct predictions and rises more when the odds were long: their announcement explains that “correct predictions at lower odds will increase a traders Elo by more than correct predictions at higher odds.” It sits on a serious data layer with full position histories, trade feeds, and entity labels, and it reflects a framing this site shares: accuracy over raw profit. The announcement makes the contrast itself, noting the top P&L trader at the time held a mid-table rating on a 52.9% win rate.

The limits, in Arkham’s own words

The announcement states that “ratings do not take bet sizing into account,” and its launch #1 was a trader of crypto up/down 5-minute markets at 64.3% across 2,644 bets. Both facts matter for how you read the board: a size-blind rating cannot distinguish a forecaster risking real capital from one grinding minimum bets, and 5-minute price series reward reflexes and structure rather than judgment about events. There is also, as of 2026-07-22, no published graded record or out-of-time backtest behind the ratings, and one global rating rather than per-category depth.

The genuine alternatives, verified 2026-07-22

• OVERROUND (this site): skill-graded category leaderboards scored against the prices actually paid, alerts from the top-graded wallets, and the two things none of the tools below carry: a public graded ledger of every alert ever sent and a pre-registered out-of-time validation. Free board and wallet checker; alerts from $19/month.
• Unusual Whales Predictions (Paid (pricing on their site)): Insider- and whale-flow tracking for Polymarket from the Unusual Whales brand, live since January 2026. Strength: Large retail distribution and a mature alerting culture. Gap: Positioning-based rather than accuracy-graded; no public graded record of what its flags returned.
• Polymarket Analytics (Free tier; paid tiers on their site): P&L and win-rate leaderboards with watchlists; widely cited in press coverage of big Polymarket winners. Strength: The reference surface for official-style P&L rankings. Gap: Ranks by profit, the metric that rewards bankroll and luck; no price-relative skill adjustment.
• Convexly (Free analyzer; paid Researcher tier): A skill-or-luck wallet analyzer scoring calibration, conviction, and discipline against a frozen 8,656-wallet reference cohort, with watchlists and a weekly digest. Strength: Methodologically serious, and it publishes its failed forward tests, which deserves respect. Gap: A reference cohort of 8,656 wallets against millions gradable; no alerts product and no graded alert ledger.
• Shadower ($27/mo or $319/yr, 3-day trial): Copy-trading execution: mirrors chosen wallets' Polymarket trades in about two seconds via the official API. Strength: Fast execution with trade-only keys; a real trial. Gap: An execution product rather than an evaluation one: it mirrors whoever you choose and does not grade whether they are worth mirroring.

Different tools fit different needs: pure execution, whale surveillance, and free ratings all have honest use cases. The comparison OVERROUND invites is narrow and checkable: which of these publishes a graded record of its own output.