What is the relationship between Brian Hartzer and Westpac in the context of the input sentence. Choose an answer from: product/material produced; manufacturer; distributed by; industry; position held; original broadcaster; owned by; founded by; distribution format; headquarters location; stock exchange; currency; parent organization; chief executive officer; director/manager; owner of; operator; member of; employer; chairperson; platform; subsidiary; legal form; publisher; developer; brand; business division; location of formation; creator.

Westpac Banking Corp's chief executive Brian Hartzer has been urged to set out a plan for cost reductions at the bank's strategy update on Monday, including reducing the number of branches, which has been inflated since the acquisition of St George during the financial crisis.

Answer: employer