For options, the security subject to being purchased or sold upon exercise of an option contract . For example, IBM stock is the underlying security to IBM options. For Depository receipts , the class , series and number of the foreign shares represented by the depository receipt.
UNDERLYING SECURITY
Meaning of UNDERLYING SECURITY in English
Campbell R. Harvey. Hypertextual finance English glossary. Английский словарь гипертекстовых финансов. 2012