Insurance broker Aon has agreed to buy human-resource consulting and outsourcing company Hewitt Associates in a cash-and-stock deal valued at about $4.9bn (€3.9bn).

The deal will nearly triple the size of the Aon's consulting operations, making it a $4.3bn business by revenue. Aon Hewitt, as the consulting and outsourcing operations will be known, will be run by Hewitt chairman and chief executive Russ Fradin.