Sharp vs Square

Sharp = sophisticated, model-driven, value-focused bettors who beat the market. Square = casual, narrative-driven bettors. Books treat them differently — sharps get limited; squares get courted.

Sharp and square are sportsbook industry shorthand for sophisticated vs casual bettors.

Sharp bettors: - Use models and probability rigor - Bet for value (positive expected value) not entertainment - Track closing line value as their primary skill metric - Get limited or banned from sportsbooks quickly because they beat the books

Square bettors: - Bet on favorites, popular teams, and parlays - Pick based on narratives ("Lakers are due") not probability - Don't track CLV or compare prices across books - Get courted with bonuses, promos, and free bets because they lose long-term

The books make their money from squares and try to protect themselves from sharps via limits. The classic "sharp move" is a sudden large bet on an unpopular side, after which the line moves toward the sharp's position — sharps' bets are signal, squares' bets are noise.

Kalshi as an exchange doesn't differentiate. Sharps and squares trade against each other at the same prices, with the spread + fee being the cost. This is one reason why Kalshi often has SHARPER pricing than sportsbooks — the prices reflect actual market consensus, not book risk management against squares.

SportsBookISH's Skill Score is designed to identify sharp behavior: high CLV, positive ROI, low Brier score on closed bets.

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