UPDATE 1-Blackstone raises $22-billion fund, its largest ever -source

(Adds details on Blackstone anticipating fund will be largest ever)

April 3 (Reuters) - Blackstone Group LP, the world largest alternative asset manager, has so far raised over $22 billion for its latest flagship private equity buyout fund, a person familiar with the matter said on Wednesday.

The New York-based firm, led by cofounder Steve Schwarzman, expects to conclude the fundraising later this year for its eighth buyout fund, said the source, requesting anonymity as the details are private.

Blackstone does not have a firm target in mind but it anticipates the fund will be the largest ever of its kind, overtaking the $24.6-billion fund raised by Apollo Global Management in 2017, the source added.

Blackstone President Jon Gray had said in January the firm expected the fund to exceed $20 billion in size.

A spokeswoman declined to comment on the fundraising, which was reported earlier by Bloomberg.

Blackstone, which had $44.4 billion in private equity funds it had raised but yet to invest at the end of 2018, has been pursuing several large leveraged buyouts in recent years.

Last year, it purchased a majority stake in the Financial and Risk business of Thomson Reuters Corp, the parent company of Reuters News, in a $20-billion deal.

Among its purchases so far in 2019, it has partnered with Hellman & Friedman to acquire human resources applications provider Ultimate Software Group Inc in an $11 billion buyout and for the acquisition of German online listings company Scout24 AG.

At the end of 2018, Blackstone had $472.2 billion in total assets under management.

The fundraising also comes as Brookfield is bulking up in size to rival Blackstone, last month agreeing to buy most of Oaktree Capital Management.

(Reporting by Joshua Franklin in New York Additional reporting by Bharath Manjesh in Bengaluru; Editing by Maju Samuel and Nick Zieminski)