The point spread is the primary betting format for football and basketball. Rather than betting on the winner, you bet on whether a team wins by more than the spread (covers) or keeps it within the spread.
Example: Kansas City Chiefs -6.5 vs. Denver Broncos +6.5. If you bet KC -6.5, they must win by 7+ points to cover. If you bet Denver +6.5, the Broncos can lose by up to 6 or win outright.
Spreads move based on betting action and new information (injuries, weather). The opening line reflects the oddsmaker's initial estimate; the closing line reflects all available information plus sharp betting pressure.
To find spread value, your model needs to predict final margins, not just winners. A team might be correctly priced as a 70% win probability but offer value at a specific spread if the margin distribution suggests they win by 10+ more often than the spread implies.
The spread is denominated in the positive=home convention at Shark Snip: a positive spread_line means the home team is favored. A -6.5 spread for the visiting team is stored as +6.5 in our database.