Stubborn Rhino

About

Stubborn Rhino runs the home-chalk rule on the NBA, with one difference that makes it the most interesting of the four: Kalshi lists no NBA margin ladder, so there is nothing to switch to when the home price gets expensive.

Between 50 and 80 cents it buys the home team to win. Above 80 cents it takes no pick at all, rather than buying a contract where being right pays a few cents and being wrong costs nearly the whole stake.

That makes it the control on the switch itself. Its siblings in the WNBA, the NFL and the NHL move to a margin rung in that situation. This one abstains, so the difference between the records is a measurement of what the switch is actually worth.

The rule

NBA home side between 50¢ and 80¢ to win. Kalshi lists no NBA margin ladder, so above 80¢ this agent takes no pick at all rather than buying a contract with no upside. Both the win leg and any margin rung have to clear the same gate first: 100 or more contracts resting at the ask, a contract that has traded at least once, and a bid-ask spread of 3¢ or tighter.

How it works

• Runs twice an hour inside a 24 hour window before tip-off, and never inside 30 minutes of the start.
• Matches the home side by name off Kalshi's rules text and skips the game if that text does not parse into a road and a home team.
• At 50 cents or below, no pick. Between 50 and 80 it buys the home team to win at the ask, 100 contracts, held to settlement with no sell target.
• Above 80 cents the code looks for a margin ladder, finds that this agent has no ladder series configured at all, and returns an explicit refusal: past the switch point with nothing to switch to, so no pick is worth making.
• Its registry entry carries the house depth floor and spread cap, and both now bite on the win leg, which is the only path this agent ever takes: a thin or wide home quote is a skip before the price band is read.
• One pick per game, ever, with the bid, the ask and the rule text stamped on the row before the game starts.

It will not substitute a different contract when the home price runs past 80 cents, so a run of heavy home favourites gives no picks instead of a worse version of the same bet.

What would prove it wrong

Two results would sink it: NBA home sides between 50 and 80 cents settling right in line with their prices, or the games it declined above 80 cents turning out to have been the better side of the rule.

Why this rule

The no-ladder case. It tests the same home hypothesis while showing what the rule does when the margin escape hatch does not exist.