Definition
A steam move is a fast, market-wide odds move caused by synced money hitting the same side across multiple sportsbooks. It often starts when respected bettors, betting groups, or automated accounts attack a price before books fully adjust.
For negative American odds, implied probability is:
odds / (odds + 100)
For positive American odds:
100 / (odds + 100)
A move from -110 to -140 changes implied probability from 110 / 210 = 52.38% to 140 / 240 = 58.33%.
Worked Example
A sportsbook opens Team A -110. A bettor risks $110 to win $100.
Within two minutes, several books move Team A to -125, then -135, then -140. The original -110 ticket still pays $100 profit on a $110 stake, but the same bet at -140 requires risking $140 to win $100.
The bettor who took -110 holds a better number than the current market by 30 cents. That price difference matters even if the bet loses, because long-term betting value comes from consistently beating the closing market.
Why It Matters
Steam moves help a bettor identify when the market is rapidly correcting a stale price. The edge comes from acting before the move finishes, not from chasing a worse number after the market has already adjusted.