Interest income rose nearly six times to $28 million in the first quarter ended March, primarily due to interest earned on $5 billion investment of debt proceeds used to fund the purchase of NFP. Last year, Aon agreed to buy privately held NFP in a deal valued at about $13.4 billion to tap the fast-growing middle-market segment of insurance brokerage, wealth management and retirement plan advisory. Fiduciary investment income, which rose to $79 million in the quarter from $52 million a year ago, refers to interest earned on funds held in a fiduciary capacity by entities acting in a custodial role.