Observer - A concept used in radar research, applicable to trading, in how often and what manner detection or radar contact is achieved.

Off Farm - The amount of stocks held by nonproducers including supplies held at mills, elevators, terminals, and processors.

Offered (Selling) Rate - Exchange rate at which dealers are prepared to sell foreign exchanges in the market and at which potential buyers are therefore able to buy foreign exchange from those dealers.

On-Balance Volume - Plotted as a line representing the cumulative total of volume.

OPEC - Organization of Petroleum Exporting Countries.

Open Account - This is a method of settling payment for trade transactions.

Open Policy (OP) - A type of insurance policy intended to cover an indefinite number of future individual shipments.

Open Position - Difference between total spot/forward purchases and spot/forward sales in a currency on which an exchange risk is run, or the difference between the totals of foreign currency assets and liabilities.

Open Trades - Current trades that are still held active in the customer's account.

Opening Call - A period at the opening of a futures market in which the price for each contract is established by outcry.

Opening Range - The range of prices that occur during the first 30 seconds to five minutes of trading, depending on the preference of the individual analyst.

Opportunity Costs - Income foregone by the commitment of resources to another use.

Optimization - A methodology by which a system is developed with rules tailored to fit the data in question precisely.

Option - A contract that provides the right but not the obligation to buy or sell a specified amount of a security within a specified time period.

Optional Cash Purchase - Buying additional shares made through the dividend reinvestment account.

Optional Term Contracts - These forward exchange contracts usually have an option period between 15 and 30 days.

OR - Owner’s risk. Variations are: ORB - owner’s risk of breakage; ORF - owner’s risk of fire; ORL - owner’s risk of loss (or leakage)

Order - The number of days of past price history used to predict the following day's price.

Oscillator - Technical indicator used to identify overbought and oversold price regions. An indicator that detrends data, such as price.

Out Trade - A mismatched trade between two traders in the pit, and which is settled the next day.

Outdata - The result (singular) stemming from a statistical test.

Outlier - A value removed from the other values to such an extreme that its presence cannot be attributed to the random combination of chance causes.

Outright - An ‘outright (forward)’ is the purchase or sale of foreign currency for delivery at any forward date beyond two working days ahead.

Outside Reversal Month - A month in which the recent monthly trading range exceeds the previous month's range and closes opposite (reverses) the previous month's close.

Overbought/Oversold Indicator - An indicator that attempts to define when prices have moved too far and too fast in either direction and thus are vulnerable to a reaction.

Overdue - A bill of exchange is said to be overdue when the time for its payment has passed, or if it is a bill payable on demand when it appears to have been in circulation for an unreasonable length of time as defined in the Bills of Exchange Act.

Overfitting - A model developed with rules tailored to fit the historical data precisely.

Overshoot - To pass beyond or over a specific targeted level.