An increased emphasis on benefits-related offerings is paying off for Aon P.L.C.

The London-based broker reported 2014 brokerage revenue of $12.02 billion, a 2.0% increase over a year earlier, making Aon No. 2 in Business Insurance's 2015 ranking of the world's largest insurance brokers.

Aon's commercial retail brokerage revenue dropped 2.5% to $5.26 billion while its employee benefits revenue grew 10.8% to $2.68 billion. Services revenue grew 5.6% to $2.61 billion, but reinsurance revenue dropped 2.1% to $1.47 billion.

Analysts agree that its private health insurance exchanges — Aon Active Health Exchange and Aon Retiree Health Exchange — are a plus for Aon, although there's no consensus about how much they added to the bottom line last year.

Meyer Shields, managing director at Keefe, Bruyette & Woods Inc. in Baltimore, said the performance of the private exchange is Aon's biggest strength.

“As that business becomes more profitable, I think that's an area where Aon's doing very, very well and people are enthusiastic about it,” Mr. Shields said.

“Our private health exchange solutions have become increasingly attractive options for companies because they leverage competition to bend the cost curve for companies, while delivering more choice, affordable care and a great experience to their employees,” Aon President and CEO Gregory C. Case said in an email. “We continue to make great strides with our full spectrum of benefit strategies and funding choices in the health care space,” he said. “In 2014, our private health exchange market for active employees and retirees increased by over 60% to more than 1.2 million employees, retirees and their eligible dependents across more than 100 companies across 19 industries.”

For Aon, the exchanges have “been a great source of positive publicity,” said J. Paul Newsome, managing director at Sandler O'Neill & Partners L.P. in Chicago. “The stock has definitely gone up when they've announced big additions to the exchange, and they have had significant enrollment in the exchange. That said, we don't know the profitability” of the exchanges.

Mr. Newsome said Aon and other brokerages face an issue of “the general sort of mediocre growth” that's “not bad but not good, either,” particularly with softening commercial insurance rates.

He also said Aon's 2012 decision to redomicile its headquarters to London from Chicago resulted in a “fairly dramatic decline in its tax rate, and one of the questions people have generally is how sustainable is that low tax rate.”

“The plus side is you actually haven't seen a lot of problems,” Mr. Newsome said. “They have been able to eke out some incremental profit margin improvements. You've had relatively few surprises, and that has a value in and of itself. They deserve a decent amount of credit for consistency in results.”

“We're sticking to our knitting, with an intense focus on our clients,” said Mike J. O'Connor, Chicago-based CEO of Aon Risk Solutions. This involves two dimensions. One is, “How do we continue to bring industry and product expertise to our clients? Our strategy has been to continue to invest in data and analytics,” he said.

The other dimension is “we see opportunity in issues around the world, such as health and benefits around the globe,” Mr. O'Connor said. “Our health and benefits practice is relevant to all of our clients and our future clients regardless of social system, how do we make sure we're bringing the best of Aon to our clients.”

“"Our objective is to spend time with our clients and understand what they are trying to get done,” he said.

Mr. Case said Aon continues to invest in innovative technology that “reinforces our position as a strategic adviser and helps us deliver differentiated solutions to clients.”

He cited as an example Aon Inpoint, a global database of risk and placement information that provides insight into more than $119 billion of global premiums.

Mr. Case added that Aon is making similar investments at its Aon Benfield Group Ltd. reinsurance brokerage unit and “we're excited to launch ReView, a reinsurer dashboard and strategic consulting platform that helps reinsurers be more effective markets for ceding-company clients.”