Insurance brokerage Aon Corp said it plans to focus on stock buybacks as it seeks to boost shareholder returns.“We do not believe there’s a significant acquisition on the horizon,” Aon’s chief financial officer Christa Davies said on Friday on a conference call with analysts to discuss the Chicago-based broker’s fourth-quarter and full-year results for 2011.Aon, which has offices in Bermuda, saw revenue jump to $11.29 billion in 2011, a 32.7 percent increase over that of a year earlier, due in large part to its purchase of Hewitt Associates Inc.Revenue for its Aon Risk Solutions brokerage and risk management unit increased 6.2 percent over that of 2010 to $6.82 billion, while revenue for its human resources solution unit increased 113 percent to $4.5 billion. Retail brokerage income in 2011 from fees, commissions and other sources rose 7.7 percent from that of a year earlier to $5.30 billion.Aon said the overall rise stemmed from a 29 percent increase in commissions and fees resulting from acquisitions, primarily of Hewitt, net of dispositions and a two percent increase in organic revenue driven by Aon Risk Solutions, as well as a two percent favourable impact from foreign currency exchange rates.Aon’s net income for 2011 increased 38.7 percent to $979 million for the year.For the fourth quarter, Aon’s total revenue increased three percent to $3 billion. Retail brokerage income rose 3.5 percent to $1.47 billion, while net income for the fourth quarter increased 19.4 percent to $277 million.“Our fourth-quarter results reflect 15 percent growth in earnings as highlighted by organic growth across all major businesses and the continued delivery of synergy savings related to Aon Hewitt,” said Aon CEO Greg Case in a statement. “While macroeconomic conditions remain challenging globally, we are firmly on track to deliver improved growth in 2012, our restructuring programmes will deliver cost savings, and we have solid financial flexibility that will drive increased shareholder value, as highlighted by the repurchase of $828 million of common stock in 2011.”Aon recently announced that it would move its headquarters from Chicago to London in order to strengthen the company’s global platform.