Glencore's top management, led by chief executive Ivan Glasenberg, is starting several days of meetings with big U.S. fund managers who could support its flotation, two people familiar with the matter said.

The meetings highlight how the world's largest commodity trader is continuing intensive preparation for a possible listing in London and Hong Kong, despite market turmoil scuppering share issues across the world.

The meetings, beginning on Monday , are partly aimed at securing so-called cornerstone investors, the people said.

Such investors underpin a listing by agreeing in advance to buy a big stake and to hold it for months, and are a common feature in Hong Kong flotations.

Glencore, valued earlier this year by one analyst at about $60 billion, wants to swap a partnership structure for a public listing. That would help it pursue bigger deals -- including a possible merger with Xstrata Plc , the Swiss miner it already part-owns.

The visit is likely to include New York and Boston, the biggest U.S. centers of equity investing.

But it is not clear whether the Glencore delegation will meet with investors who have already backed the Swiss trader.

Three U.S. asset managers -- New York-based BlackRock , The Capital Group Cos of Los Angeles and Boston-based Fidelity Investments -- were among a select group that bought $2.2 billion in convertible bonds from Glencore in December 2009.

Glencore also sold some of the bonds, which convert into equity if it stages an initial public offering (IPO), to First Reserve Corp, the energy-focused private equity firm that has U.S. offices in Greenwich, Connecticut and Houston, Texas.

Glencore declined to comment.

INVESTORS EXPECT IPO

Meanwhile, a Reuters poll of fund managers published on Monday found that Glencore is expected to cling on to plans for a bumper London listing by the end of May, despite global stock market uncertainty.

The survey of 10 fund managers from investment houses controlling total global assets of $3 trillion found a majority assuming the deal will proceed before a summer listings hiatus, despite the near panic on markets caused by the Japan disaster.

Six of the 10 said they thought it unlikely Glencore would peg back its long-term plans for an IPO, with some suggesting a backlash against nuclear energy could boost its oil and coal trading activities.

Only two said they thought recent events pose a serious threat to the expected timetable. (Additional reporting by Kylie MacLellan; editing by Alexander Smith)

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