Commodities giant Glencore is set to launch a roughly $10 billion public offering on Thursday, when it outlines plans for a May market debut that will make multi-millionaires of its partners and boost its deal-making capacity.

Sources close to the situation say the secretive Swiss-based firm -- the world's largest commodities trader -- is preparing to publish an Intention to Float, ending months of frenzied speculation as it details its plan to sell a stake of up to 20 percent in a dual London-Hong Kong listing.

Fueled by the lofty prices in many of the raw materials Glencore buys, mines, ships and sells, the float could be one of the biggest in London's history, propelling the firm into the FTSE 100 bluechip index and into the pension funds and investment portfolios of millions.

Glencore, valued earlier this year by an analyst at $60 billion, has consistently declined to comment on the timing of the float and its potential valuation.

A convertible bond issued in 2009 valued the company at about $35 billion, before conversion, but strong profits since then will have led to a significant increase.

At current market values, Glencore's listed stakes alone are worth around 31 billion pounds. These include just over 34 percent of Swiss miner Xstrata and just under 9 percent of Russian aluminum giant RUSAL <0486.HK>.

LIFTING THE VEIL

Notoriously discreet, Glencore and its executives will be stepping into the limelight after four decades of closely guarded privacy with the bumper IPO.

But by scrapping its long-standing partnership structure in favor of life as a public company, Glencore will be able to reward its 500 or so partners and to fund more -- and larger -- acquisitions, including a possible merger with Xstrata.

Glencore, which owns extensive mining operations, oil fields, grain elevators and more ships than Britain's Royal Navy, has so far taken an opportunistic approach to deals, often snapping up lower tier assets than its diversified miner rivals, but at much keener prices.

The Swiss-based mining and trading firm is also expected to name a new non-executive chairman on Thursday -- a requirement for the listing. Three candidates were on the shortlist days before the document was published, including former French Foreign Legionnaire Simon Murray.

The new chairman will sit on an eight-strong board alongside Chief Executive Ivan Glasenberg.

Glencore is expected to sign up cornerstone shareholders to its IPO, but these may be made public only when it publishes its prospectus next month.

After months of volatility, investors remain jittery, but on the credit markets at least, they have shown signs of increased confidence.

Five-year credit default swaps on Glencore have continued to tighten, hitting their lowest levels since February 2010 earlier in the week and touching 153.7 basis points on Wednesday, Markit data showed. That price means it costs 153,700 euros a year to insure 10 million of debt against default.

Glencore has yet to officially mandate its advisors, but Citi , Morgan Stanley and Credit Suisse are likely to serve as joint global co-ordinators, with Bank of America Merrill Lynch and BNP Paribas as bookrunners.

Barclays Capital , Societe Generale and UBS are likely to make up a third tier of banks advising, according to sources familiar with the matter.

(Reporting by Clara Ferreira-Marques; Additional reporting by Quentin Webb; Editing by Jon Loades-Carter)

United kingdom BNP Paribas