Principal Financial Group Inc. on Thursday reported second-quarter net income available to common shareholders of $322.3 million, or $1.10 per share, up 34 percent from $241.1 million, or 81 cents, in the previous year’s quarter. Operating earnings increased 4 percent to $337.1 million for second quarter 2016, compared with $323.9 million for second quarter 2015. A quarterly stock dividend of 41 cents per share for third quarter 2016 was authorized by the board. “I’m very pleased with the team’s continued successful execution of our strategy,” said Dan Houston, Principal’s chairman, president and CEO. “Business fundamentals, such as investment performance, remain strong, contributing to more than $11 billion of net cash flows through midyear 2016.”