* Justice ups size of offering after securing third founder
* William Ackman's Pershing buys a third of the deal
* Trio raise 900 million pounds to fund acquisition
LONDON, Feb 14 (Reuters) - Billionaire Nicolas Berggruen's Justice Holdings JUSH.L fund raised a greater than planned 900 million pounds ($1.45 billion) from its listing on Monday, after hedge fund manager William Ackman bought in to the deal.
Ackman, who joined the German-American investor and his business partner Martin Franklin as a company founder during the fundraising, bought almost a third of the 90 million shares sold, through his Pershing Square funds, Justice said on Monday.
Last week sources close to the deal told Reuters that Berggruen and Franklin, who each bought just over 3 million shares in Justice, had been seeking to raise around 700 million pounds from the London listing and were offering the stock at 1,000 pence per share. [ID:nLDE7160GA]
The trio will use the funds to buy a business with an enterprise value between 1 billion and 7 billion pounds, Justice said in a statement, adding that its target would not be limited to a particular industry or geographic region.
Justice shares, due to begin trading unconditionally on Feb. 17, were quoted down 0.5 percent at 995 pence by 1222 GMT.
The fund, an acquisition vehicle incorporated in the British Virgin Islands, will be chaired by former British financial services minister and fund manager Paul Myners, and also counts U.S. economist Nouriel Roubini among board members.
Justice will be the third investment vehicle set up by Berggruen, dubbed the homeless billionaire for living in hotels.
His first, Freedom Acquisitions, bought a stake in hedge fund group GLG Partners GLG.N, while his second, Liberty Acquisitions, bought insurer Pearl -- now known as Phoenix (PHNX.L) -- and last year paid $900 million for a majority stake in Spanish media group Prisa, owner of daily newspaper El Pais.
Berggruen, the son of German art collector Heinz Berggruen, last year bought German department store chain Karstadt.
Barclays Capital and Citigroup were joint global coordinators and joint bookrunners on the Justice offering. (Reporting by Kylie MacLellan; Editing by Will Waterman) ($1 = 0.6223 pound)