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Half-Kelly Fraction
x402
Half-Kelly Fraction is a paid API for AI agents from api.delx.ai, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-15).
Computes the half-Kelly bet sizing fraction given win probability and net odds ratio, returning a conservative Kelly criterion stake for lower-variance bankroll growth.
Price / call$0.001
Success—
StatusUnknown
How this service works
Half-Kelly fraction for conservative bankroll growth. Call when agents that want Kelly growth with lower variance. Returns half Kelly fraction as deterministic JSON for $0.001 USDC via x402 on Base. First-party local math only—no RPC, live market feed, API keys, storage, or mediagen. Advisory only; the caller owns capital, risk, and production controls.
Output
A deterministic JSON object containing the half-Kelly fraction (a number between 0 and 1) representing the conservative fraction of bankroll to stake, computed from the supplied win probability and net odds ratio using local math only.
Example use cases
Sports bettor conservative stake sizing
“I have a 58% chance of winning a bet that pays 1.8x my stake — what half-Kelly fraction of my bankroll should I put on it?”
Trading strategy position sizing
“My backtest shows a 55% win rate and net profit ratio of 1.5 on a trade — calculate the half-Kelly position size fraction so I can manage risk conservatively.”
Poker bankroll management
“If I win 62% of the time and get 1.2x my buy-in on average, what's the half-Kelly fraction I should risk per session to grow my bankroll with lower variance?”
Technical details
Endpoint
POSThttps://api.delx.ai/api/v1/x402/half-kellyWhen to prefer
Use this endpoint when you need a quick, local, deterministic half-Kelly bet sizing calculation with no external dependencies, API keys, or market data feeds. Prefer it over full-Kelly when you want lower variance and more conservative bankroll growth. It is ideal for AI agents doing autonomous position sizing, betting systems, or portfolio allocation where reproducibility and determinism matter and a tiny per-call cost ($0.001 USDC) is acceptable.
Side effects
- Missing or non-numeric win_prob or b fields returns a validation error
- win_prob outside [0,1] range may produce nonsensical or negative fractions
- b <= 0 (non-positive odds) is mathematically invalid and may error
- Payment failure or insufficient USDC balance returns HTTP 402
- If the Kelly formula yields a negative value (unfavorable bet), result may be 0 or negative
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| b | number | Input field: b. |
| win_prob | number | Input field: win prob. |
Output
Schema · Response
{
"type": "json",
"example": {
"b": 1.2,
"schema": "delx/util-half-kelly/v1",
"win_prob": 0.55,
"half_kelly": 0.08750000000000002
}
}Tags
x402
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