Refer to the input text as context and select the correct relationship between 'Willis Group' and 'insurance broker' from the available options.
Options: publisher, position held, industry, developer

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.
industry