DEFINITION of 'Touchline'
The highest price that a buyer of a particular security is willing to pay and the lowest price at which a seller is willing to sell, at a given time in the trading day. The touchline therefore specifies the best bid or ask for a particular security at any point in time. Very liquid securities will generally have a narrow bid-ask spread, while illiquid securities will have a wide spread.
BREAKING DOWN 'Touchline'
For example, if security A has various buyers who are bidding $5, $5.10 and $5.15 for it, the touchline bid price would be $5.15. At the same time, if security A has various sellers at $5.20, $5.30 and $5.35, the touchline ask price would be $5.20. The bid-ask spread on security A is therefore $5.15 (bid) / $5.20 (ask).