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.

In early March, when merger talks were under way between Towers Watson TW, -0.76% and insurance broker Willis Group Holdings PLC WSH, -1.82% , Haley exercised 106,933 stock options and sold the underlying shares for a $9.7 million profit, according to regulatory filings.

Answer: industry