* Minimum valuation seen below $50 bln including new funds
* Eton Park, C. Suisse, Pictet also backing float -sources
* Bond owners BlackRock, GIC, Zijin, Fidelity also lined up
* "Cornerstone" investors may take nearly 30 pct of IPO
LONDON, May 3 (Reuters) - Abu Dhabi's Aabar Investments will be the biggest of at least 10 "cornerstone" investors backing the $12 billion flotation of Glencore, the Swiss commodity trader, people familiar with the matter said on Tuesday.
Aabar, majority owned by the emirate's International Petroleum Investment Co (IPIC), will be joined by hedge funds Och-Ziff Capital Management (OZM.N) and Eton Park, Swiss banks Credit Suisse, Pictet and UBS, and a quartet of Glencore's existing convertible bond investors, the people said.
Glencore [GLEN.UL], the world's largest diversified commodity trader, is preparing to float in London and Hong Kong, with a prospectus and an initial price range due on Wednesday.
Glencore is likely to price the IPO towards the lower half of the wide $45 to $73 billion value range implied by numbers released by the company in its intention-to-float document, and below a widely cited $60 billion valuation.
People familiar with the matter said a more modest range would help Glencore convince some reluctant investors who worry they will be on the wrong end of a deal to allow the company's star traders to sell out at the top of the market. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
For a Breakingviews on Glencore click on [ID:nN03100599]
One person familiar with the matter said on Sunday that the range could place a minimum value on the company of less than $50 billion including new funds.
Reuters was first to reveal the make-up of Glencore's likely investor base two days ago, when it reported that an Abu Dhabi vehicle, big hedge fund managers and Swiss banks were set to serve as "cornerstones", alongside several holders of the convertible bonds.[ID:nLDE7400CE]
Such investors back many Asian listings, committing to take large, guaranteed stakes and hold them for at least six months.
The cornerstones could buy nearly 30 percent of the shares sold -- or some $3.6 billion worth, if the listing raises its maximum target of $12.1 billion, making it London's biggest ever.
The four existing bondholders who will commit extra funds are asset managers BlackRock (BLK.N) and Fidelity, the Government of Singapore Investment Corp. (GIC), and China's Zijin Mining (601899.SS), the people familiar with the matter added.
The precise identities of the new backers were reported earlier on Tuesday by the Financial Times and the Wall Street Journal. The FT said Aabar would commit at least $850 million, and buy at least another $150 million during bookbuilding.
Credit Suisse and UBS are among the banks underwriting the listing for Glencore, which is led by Chief Executive Ivan Glasenberg.
Credit Suisse, Fidelity, Glencore, Och-Ziff and UBS declined to comment. The other backers were not immediately available for comment. (additional reporting by Stanley Carvalho in Abu Dhabi, Elzio Barreto in Hong Kong, Svea Herbst-Bayliss in Boston and Martin de Sa'Pinto in Zurich; editing by Sitaraman Shankar)