COLUMBUS, Ga. ( TheStreet) -- Aflac ( AFL) topped Wall Street expectations with its second-quarter results as revenue rose nearly 16% year-over-year. After the closing bell, the disability insurance provider reported operating earnings of $639 million, or $1.35 a share, in the three months ended June 30, up from a year-ago profit of $562 million, or $1.20 a share. The operating figure excludes realized investment losses and gains, as well as other non-recurring items. The average estimate of analysts polled by Thomson Reuters was for earnings of $1.33 a share in the June period. Including realized investment losses and gains, Aflac earned $581 million, or $1.23 per share, up from a year-ago equivalent profit of $314 million, or 67 cents per share. Total revenues rose 15.5% to $5.0 billion in the latest quarter from $4.3 billion last year because of an uptick in U.S. and Japan-based sales. The company has a "significant" portion of its business in Japan, making its operations especially sensitive to fluctuations in the dollar-yen exchange rate. "Aflac Japan's operations have remained strong while producing significant sales growth," said Daniel Amos, the company's chairman and CEO, in a press release. "As a result, we believe we are well-positioned to achieve our full-year sales target in Aflac Japan, our largest segment." Amos added: "Sales in the United States continue to be challenged by the extended weak economic environment." For the third quarter, Aflac forecast operating earnings of $1.35 to $1.38 per share. That outlook compares to Wall Street's current consensus estimate for earnings of $1.37 a share in the September period. The company also declared its regular quarterly dividend of 28 cents a share for the third quarter, payable on Sept. 1 to shareholders of record on August 18. Aflac shares closed down 33 cents at $50.71, but the stock was edging higher in after-hours action. Tuesday's volume of 5.7 million was right in line with the issue's trailing three-month daily average. Year-to-date, the shares are up 10.4%. -- Written by Maria Woehr in New York.