(Reuters) - Blackstone Group LP , the largest publicly listed alternative asset manager, said on Thursday that its third-quarter earnings increased by 3 percent year-on-year as its fee revenue and profits from sales of its holdings rose. Blackstone, whose investments include The Weather Channel, Pinnacle Foods and SeaWorld Entertainment Inc , said economic net income (ENI), a metric of its profitability that takes into account the mark-to-market valuation of its portfolio, was $640.2 million, up from $621.8 million in the third quarter of 2012. This translates into ENI per unit of 56 cents, slightly higher than the average 55 cents forecast by analysts in a Thomson Reuters poll. Distributable earnings, which show actual cash that is available to pay dividends, rose in the third quarter 59 percent to $312.7 million. Total assets under management hit a record $248 billion as of the end of September, up 21 percent year-on-year. Fee-earning assets under management rose 12 percent to $188.7 billion. Blackstone declared a quarterly distribution of 23 cents per common unit. (Reporting by Greg Roumeliotis in New York; Editing by Gerald E. McCormick)