Glencore International Plc has tightened guidance for its planned $11 billion initial public offering (IPO), pushing up the mid-point of the marketing range, a source said, in a sign the commodities trader has seen stronger demand at the higher end of an indicative range.

Glencore's IPO has entered the home stretch after a two-week road show, during which time commodity prices nosedived, raising some doubts about the success of the offer. But Glencore closed the books one day ahead of schedule, suggesting that the offer continued to generate interest.

Glencore narrowed the IPO price range to 520-550 pence per share from its previous guidance of 480-580 pence each, a source with direct knowledge of the matter told Reuters on Monday.

The source said the book is multiple times covered, adding that the company and banks are confident the deal can be done at the revised price range.

Underwriters usually send out a new pricing guidance to reflect the range in which the offer has attracted maximum demand.

The recent downturn in commodities markets had raised some doubts about whether the IPO will continue to attract the same demand. The new guidance indicates the company is not willing to sell shares at the bottom of the band as some investors had hoped.

The new range lifts the mid-point of the offer to 535 pence from 530 pence.

Some European fund managers were betting that the rout in commodities markets would give institutional investors the pricing power on the IPO.

Glencore is set to close the IPO books on Tuesday, one day ahead of schedule, with final pricing due on May 19.

Order books for shares in Glencore, the world's largest diversified commodities trader, were fully covered within hours of the start of the sale process, but part of that success is a result of the relatively small stake in the company being placed with funds and because of Glencore's size, which makes it a must-buy for many.

Glencore has sold about a third of the offer to cornerstone investors, who have agreed to a six-month lock-up in return for a guaranteed allotment.

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