Used in the context of general equities. Assures that an individual contracts all his or her business with a sole broker by providing superior services, such as accommodating block buy and sell needs or preparing excellent research ( soft dollar lock). This usually guarantees a certain volume of business.
LOCK IN
Meaning of LOCK IN in English
Campbell R. Harvey. Hypertextual finance English glossary. Английский словарь гипертекстовых финансов. 2012