Sentence:  In the instant case, it should be noted that the petitioner did not know the exact abount of its <WSD>undermargin</WSD>, and that even after its request for a statement of account, it was only some three months thereafter that private respondents were able to comply. 
Meaning of the word marked with <WSD> tags:  A shortfall; the amount by which the value of an investment purchased on margin falls below the required maintenance amount.