Aflac ( AFL) fell shy of fourth-quarter estimates but guided higher for 2007.The Columbus, Ga., insurer made $332 million, or 67 cents a share, for the quarter ended Dec. 31, down from the year-ago $364 million, or 72 cents a share. On an operating basis, excluding realized investment gains and losses, earnings rose to 66 cents a share from 59 cents a year earlier. Analysts surveyed by Thomson Financial were looking for a 67-cent profit. The yen/dollar exchange rate did not impact operating earnings on a per-share basis for the fourth quarter. A significant portion of Aflac's business is in Japan. For 2007, the company guided to earnings of $3.28 to $3.31 a share, excluding the impact of yen moves, against the $3.27 Thomson Financial target.