BRUSSELS (Reuters) - EU antitrust regulators are set to open a full-scale investigation into Aon’s $30 billion bid for Willis Towers to create the world’s largest insurance broker, two people familiar with the matter said. The European Commission will open the probe following the end of its preliminary review on Dec. 21. Aon did not provide concessions on Monday, the deadline for doing so in the preliminary phase to address EU competition concerns, the EU competition enforcer’s website showed.- Reuters