Definition for Unmatched book
From Biology Forums Dictionary
If the average maturity of a bank's liabilities is shorter than that of its assets, it is said to be running an unmatched book. The term is commonly used with the Euromarket. Also refers to entering into OTC derivatives contracts and not hedging by making trades in the opposite direction to another financial intermediary. In this case, the firm with an unmatched book usually hedges its net market risk with futures and options. Related expressions: Open book and short book.