Utilize the input text as a context reference, choose the right relationship between Willis Group and insurance broker from the options. Options: 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.

The week's deals included the $28.3 billion purchase of insurer Chubb by Swiss insurer Ace Limited (NYSE: ACE - news ) ; the $6.8 billion acquisition of Health Net (NYSE: HNT - news ) by rival health insurer Centene; and the decision by US professional services company Towers Watson and insurance broker Willis Group to combine in a deal with an implied equity value of about $18 billion.

Answer: industry