130 THE WORK OF THE STOCK EXCHANGE
frequently, while some stocks are rising others are declining.
Thus it is quite possible for the customer’s debit balance to be
increased at the same time by rising prices on his short stock
and declining prices on his long stock. If meanwhile his debit
balance had been reduced by fully crediting against it the
market value of the short stock, his unhappy broker might
under the circumstances have to be prompt to call for more
margin in order to save himself from serious loss.
The Margin Card.—A current record of Blank’s equity in
his account—or his “margin,” -as it is more often called—is
constantly kept by the margin clerk of the brokerage house.
The broader economic significance of margins has already been
discussed in a previous chapter.’ The margin clerk keeps a
separate record for every customer of his house, and constantly
adjusts the customers’ margins as the trend of security prices
dictates. In this way the commission house is always in touch
with the amount of margin maintained by each of its cus-
tomers, and in a position to call the given customer for more
margin, or to know whether he can safely make new transac-
tions on the basis of his existing margin. The margin cards
used by different Stock Exchange commission houses differ
more or less in their details. Figure 57 represents a form of
margin card easy for the layman to understand; it cannot be
said, however, that this particular form is typical of margin
cards generally employed. The items which it contains show
the condition of Mr. Blank’s margin at the time when his
monthly statement above included was issued. It will be noted
that the securities which the customer originally owned out-
right, but which he deposited as margin, are entered exactly
like the securities which he subsequently bought on margin.
At the top of the margin card, the customer’s debit or credit
balance, and the market value of his long and short stock are
entered. These figures, as well as the margin derived from
2 See Chapter VII, p. 184.
