Trading on the London Stock Exchange between 8 a.m. and 8.30 a.m., when the market officially opens. Some market makers are willing to deal in this half hour on a limited range of stocks and shares. This tends to be speculative pre-market trading as the prices may change after the official opening.

• open auction
• open cheque
• open contract
• open credit
• open economy
• open-end credit
• open-ended investment company
• open-end trust
• opening bank
• opening prices
• opening stock
• open interest
• open-market desk
• open-market operations
• open-market value
• open-mouth operations
• open outcry
• open position
• open years
• operating budget
• operating lease
• operating profit/loss
• operating risk
• operating statement
• operating target