(1) A bond in default trades flat; that is, the price quoted covers both principal and unpaid, accrued interest . (2) Any security that trades without accrued interest or at a price that includes accrued interest is said to trade flat .
FLAT TRADES
Meaning of FLAT TRADES in English
Campbell R. Harvey. Hypertextual finance English glossary. Английский словарь гипертекстовых финансов. 2012