The nation's No. 2 banking group, KB Financial Group, said Friday its first-quarter earnings slipped more than 9 percent from a year earlier on a slipping profit margin amid falling commission income.

Net income reached 373.5 billion won ($358.8 million) in the January-March period, compared with the 411.5 billion won from the previous year, the group said in a regulatory filing. 

Net profit jumped 44 percent from three months earlier.

The group said its interest income declined on a long streak of low rates and a fall in commission income, such as fees from selling insurance policies.

The group said its net interest margin, a key barometer of profitability, came in at 2.46 percent last quarter, down from 2.73 percent the previous year.

The central bank's monetary easing cycle has weighed on market interest rates, denting local banks' interest income. KB Financial said its net interest income fell 6.5 percent on-year to 107.9 billion won.

Commission income from bancassurance and credit card services fell 14.6 percent on-year to 53.5 billion won.The group's total assets stood at 388 trillion won as of the end of March, up from 380 trillion won three months earlier.

Kookmin Bank, the flagship unit of the group, posted a net income of 258.2 billion won in the first quarter, down 12.7 percent from the previous year.

By Bae Hyun-jung and news reports (tellme@heraldcorp.com)