Test a rule against every market that has settled.
Arena has been recording every market it mirrors: the price every five minutes while it is open, and the outcome once the exchange grades it. A backtest replays your rule over that record, at the prices that were really there, and tells you whether it is an edge.
- Price snapshots
- Every 5 min
- while a market is open
- Settlements
- As graded
- won, lost or void
- Look-ahead
- None
- by construction
Where the history comes from
There is no third-party dataset behind this. The record is Arena’s own, built market by market since the app started mirroring the exchange.
- 01
Every market Arena mirrors
NFL, NBA, MLB, NHL, soccer, politics, crypto: the same Kalshi markets the app shows live, kept once they close.
- 02
The price, every five minutes
Bid and ask snapshots while a market is open, so a rule is replayed at the prices that were actually there to take.
- 03
Settlement as the exchange graded it
Won, lost or void, including markets that were cancelled: nothing is dropped after the fact.
How a backtest runs
- 01
Write the rule
In plain English or with the CLI. “Fade NBA favourites when the line moves 3¢ or more in the last hour before tip-off.”
- 02
Replay it, without look-ahead
At each decision point the rule sees only what had been recorded by then, and fills at the ask that was on the book. Fees and the spread are paid.
- 03
Read the interval, not the win rate
The answer is the edge per contract with a 95% interval over every game the rule touched. An interval that crosses zero is not an edge, however good the win rate looks.
- 04
Run it forward
Any rule can be handed to a paper account that trades it at live prices on the public board, so the record keeps growing where everyone can see it.
What an answer looks like
Here is the shape of a result for a rule that does not work yet. The mean edge is positive, which is where most people stop reading; the interval crosses zero, which is where the answer is. Rather than tune the rule until the number looks better, Arena runs it forward on paper so the record becomes real.
- Every game the rule touched counts, including the voids.
- Fills at the recorded ask; the spread is paid, as it would have been.
- The forward ledger lives on the public board, under the rule’s name.
fade NBA favourites when the line moves 3¢ or more in the last hour before tip-off
- Settled games
- 212
- 2025-26 season
- Edge per contract
- +1.8¢
- mean, at the close
- 95% interval
- −0.9¢ to +4.5¢
- crosses zero
- Verdict
- Not an edge yet
- run it forward
forward ledger
+$6.20 · 24 games · paper
Bring a rule. The record is ready.
Backtesting is in early access. Tell us the rule you want to test and we will run it with you, or hand it to an agent and let it write the rule first.