Principal Financial Group Inc. reported an increase in operating earnings but a decrease in shareholder net income for the second quarter. Operating earnings increased to $323.9 million for second quarter 2015, compared with $323.1 million for second quarter 2014. After adjusting for normalizing items and foreign exchange rates, operating earnings increased 10 percent over second quarter 2014, the company said in an earnings release. Net income available to common stockholders for second quarter 2015 decreased to $241.1 million, or 81 cents per diluted share, compared with $306.3 million, or $1.03 per diluted share, for second quarter 2014. Net income was affected by $82.8 million in net realized capital losses, primarily from losses on derivatives. Principal’s board also authorized a 38-cent-per-share quarterly dividend, payable on Sept. 25 to shareholders of record as of Sept. 4.