Flat. Without interest.  When bonds are sold flat no additional charge is made to the buyer for the
interest accrued on them; in other words, the interest is included in the sale.  When stocks lend
flat the lender has not to pay interest to the borrower of the stock. Ordinarily the borrower of stock
pays the lender the market value of the stock and the lender pays interest to the borrower on this
money.  The rate of interest paid is usually a little less than the ruling rate for call money. When a
stock is lending flat the fact signifies that this particular stock is in inadequate supply, or at least
that it is not easy to obtain by borrowers.  When a stock is lending at a premium the borrower not
only receives no interest on the money that he advances to the lender, but he also has to pay
whatever amount may be agreed upon for the use of the stock. In such a case the stock is very
scarce or very difficult to obtain.
There is another meaning to flat; when little business is done in the stock market or in any other
market the market is said to be flat.