The Blackstone Group, a hedge fund, buyout and real estate firm, is about to undergo leadership changes in two of its divisions.

John Kukral, the president, co-founder and CEO of Blackstone Real Estate Advisors, has announced he will be leaving at the end of the year.

Tom Saylak, another co-founder of Blackstone Real Estate, left the firm more than a year ago to head up Merrill Lynch's ( MER) commercial real estate business.

Blackstone recently named two co-heads for the real estate division in order to fill the gap -- Jon Gray in New York and Chad Pike in London. Both are senior managing directors at Blackstone Real Estate and serve as members of its investment committee.

On the $14 billion private equity side, Blackstone is losing Mark Gallogly, the head of the group. Gallogly plans to leave to create his own investment company with Jeffrey Aronson, a former partner at hedge fund Angelo Gordon & Co.

But here, the succession plan isn't as clear. Blackstone recently hired buyout veteran Garrett Moran to take over Gallogly's administrative duties such as hiring, training and managing 60 people in the group, according to John Ford, Blackstone's spokesman.

The bulk of the private equity investment business will be controlled by Hamilton "Tony" James, the group's president. Apparently, his role at the firm will become more and more central.

Blackstone Alternative Asset Management, the fund of hedge funds behemoth that has grown to have $9 billion to $10 billion of assets, is still run by Tom Hill, who came on board more than a decade ago after working at Lehman Brothers ( LEH) and the old First Boston.

Naturally, Hill enjoys a tremendous stable of Wall Street contacts, but mostly, he has established his franchise as a magnet for institutional money, in particular U.S. pensions.

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