David Calhoun did a lot of good turning around Nielsen‘s fortunes when he joined as CEO of the ratings company in 2006 after being a top lieutenant at Jack Welch’s GE. (In this town, that success did not trickle down to one of Nielsen’s holdings, trade mag The Hollywood Reporter, which continued to bleed money and staff under Nielsen control until it was sold off with other publications for a song three years later.) Calhoun, already set to step down as Nielsen CEO on January 1, will join Blackstone Group to head its portfolio-operations group, the Wall Street Journal is reporting today. He will be tasked with boosting some of the company’s 77 holdings while also consulting on new buyouts. He will retain the executive chairman title at Nielsen as part of the deal. Earlier this month, Nielsen said company veteran Mitch Barnes would succeed Calhoun as CEO; the ratings company has been taking steps to update its business, acquiring Arbitron for $1.3B as it wades into the cross-platform measurement game including for mobile TV, and striking a deal with previous dark horse Walmart to shepherd previously private data on the giant retailer’s sales. Blackstone was one of the PE firms who bought Nielsen, then known as VNU, in 2006, with Calhoun contributing a sizable amount of his own money into the deal. Nielsen went public in January 2011 and under Calhoun’s nearly seven-year run as boss has seen its operating income more than double to $1.7B, according to the WSJ. At Blackstone, one of the world’s biggest private equity firms, he will employ the operational efficiency standards he learned under Welch at GE. His target will be companies including the Weather Channel in Blackstone’s portfolio, which in total employs more than 600,000 and generates around $85B in annual revenue. There is no word on his compensation package for the new gig.