Lead-left bookrunner is the major bank within a bank syndicate, the group of banks who work together to underwrite a financial transaction, such as an initial public offering or a bond issue.
As syndicates have grown to include more banks, the title 'lead-left' is used to indicate the bank that has played the most important role in the transaction, and has been involved in the deal from an early stage.
The term evolved from the position of bank names in deal documentation – the most important bank being named first, in the upper left hand corner of a prospectus.
One cannot call a left-lead bookrunner the sole bookrunner if there were other bookrunners on the deal. Even if they were more junior in terms of role.
Defining the roles played within a syndicate is crucial in determining banks' league table positions. League tables are the main ways in which banks measure their performance against each other. Achieving a top ten position in a league table is also seen as an important tool for winning further client business.
Left leads have definitely played the most prominent role amongst a syndicate of banks. The term can apply to any type of transaction, be it bonds, equities or loans.
League table 'credit' is awarded commensurate with the importance of the role. Credit will be split equally among underwriters that are identified in a deal's prospectus as joint bookrunners or co-bookrunners, for example, while banks identified as 'left lead' receive more league table credit.