jump ball (plural jump balls)
- A method used to begin or resume play in basketball. Two opposing players attempt to gain control of the ball after it is tossed up into the air in between them by an official.
- After any dead ball, play shall be resumed by a jump ball, a throw-in or by placing the ball at the disposal of a free-thrower. 
- Metaphor for a contest too close to call.
- The morning after Election Day, the Oregon governor's race is still a jump ball, but ex-NBA player Chris Dudley is clinging to a slim lead.
- In the context of general equities,
- Deal in which no trading house has exclusivity (each firm is in direct competition for a piece of business).
- No preference in picking a particular side (buy/sell) of a stock as profile, indicated during the block call, indicate that the sales force could have the stock either way.