CHICAGO (Dow Jones/AP) ? Aon Corp. became the last of the three biggest insurance brokers to receive approval from the New York Attorney General and insurance regulators to accept so-called contingent commissions in some circumstances.

Like Marsh & McLennan Cos. and Willis Group Holdings Ltd., Aon?s agreement will allow it to accept the commissions, which can be based on profits, when the broker acts as an agent for the insurer. The loosened restrictions come after an industry-wide investigation into insurance-brokerage compensation that resulted in allegations of bid-rigging and price-fixing by Marsh, and others.

Chicago-based Aon and the other brokers gave up contingent commissions in 2004.

Aon said it has obtained permission from the attorneys general in New York, Illinois and Connecticut to amend its agreement. The insurance departments of New York and Illinois have also agreed.