NEW YORK (Bloomberg) ? Aon Corp., the world?s second-largest insurance broker, reported unchanged fourth-quarter profit and said it discovered ?incorrect measurement dates? for certain stock options granted in 2000 and earlier.

Net income was $224 million, the same as a year earlier, Chicago-based Aon said in a statement yesterday. Earnings excluding discontinued operations and severance costs were 67 cents a share, higher than the 63-cent average estimate of 13 analysts surveyed by Bloomberg.

Aon?s revenue rose 7 percent to $2.41 billion, outpacing a 3 percent increase in expenses, as its brokerage, consulting, and underwriting units brought in more fees and premiums. Profit would have risen had Aon not recorded a $108 million gain in the year-earlier period from selling its Swett & Crawford unit.

The company said its audit committee started a comprehensive review of stock options dating practices and plans to quantify any impact on financial reporting by March. No material effect is expected for 2005 or 2006.

?Based upon our preliminary review, the company has not found evidence of intentional misconduct or financial self-dealing, including backdating, or other manipulation of stock option pricing,? Aon said in the statement.

Revenue from brokering insurance, Aon?s biggest business, climbed 7 percent to $1.52 billion. Excluding the impact of foreign exchange and acquisitions, the increase was 2 percent. On that basis, Willis Group Holdings Ltd., the third-biggest broker, posted 7 percent growth, and Arthur J. Gallagher & Co., the No. 4 broker, had a 4 percent gain. Marsh & McLennan Cos., Aon?s biggest rival, is set to report the quarter?s results next week.

Shares of Aon fell 35 cents, or 1 percent, to $36.43 in New York Stock Exchange composite trading yesterday. They?ve risen 5.1 percent in the past 12 months, under-performing the 13 percent gain in the KBW Insurance Index. The results were released after the close of regular trading.