Tick

"Tick" has two closely related meanings in trading.

1. A price update. Every time the bid or ask quote changes, that is one tick. In a busy market, EUR/USD can tick many times a second; in a quiet session, there may be seconds between ticks. Expert advisors in MetaTrader run their main logic "on every tick", which is why they react to price changes rather than to time.
2. The minimum price increment (tick size). For most forex pairs quoted to five decimals, the smallest possible move is 0.00001, one pipette. For futures and some CFDs, the exchange or broker sets a tick size and a tick value in money.

Example

Illustrative figures: a stock index CFD has a tick size of 0.1 points and a contract value of 1 euro per point, so each tick is worth 0.10 euros per contract. A move from 18,000.0 to 18,002.5 is 25 ticks, or 2.50 euros per contract.

For EUR/USD, a move from 1.08500 to 1.08537 is 37 ticks in the "minimum increment" sense, or 3.7 pips, regardless of how many quote updates it took to get there.

Tick volume

Forex is traded over the counter, so there is no single exchange reporting total traded volume. The "volume" on most forex charts is tick volume: the number of price changes the broker recorded in each bar. It tends to rise when activity rises, so traders use it as a rough proxy for activity, but it is specific to each broker's price feed and is not actual traded size.

Practical note

Tick charts, which draw a new bar after a set number of ticks rather than a set time, are popular with scalpers. For how charts are built, see how to read candlestick charts.