Dealer	a person who buys securities for his or her account and retains them until sold to another.
Default	failure to meet financial obligations
Delivery	Failure to perform on a futures or short options contract as required by exchange rules.
Delivery Month	The specified month within which a futures contract matures and can be settled by delivery.
Delta	The amount of change of an option's price or theoretical value for a unit change in the price of the underlying security, commodity, currency, index or futures contract.
Depreciation	a decrease in price or value
Derivative	a financial instrument whose value is based on another security
Discount	(1) The amount a price would be reduced to purchase a commodity of lesser grade; (2) price differences between futures of different delivery months; (3) cash prices below the futures price.