Commodities trader Glencore is seen clinging on to plans for a bumper London listing by the end of May, despite global stock market uncertainty, according to a Reuters poll of fund managers.

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 initial public offering (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.

Most managers acknowledged heightened uncertainty as a result of conflict in Libya and Japan's nuclear crisis made the deal a tough call. And two said it was too early to tell whether a high profile equity capital markets deal like Glencore's would be hit given the unpredictability of events.

A significant proportion of the managers said recent market corrections could widen the gulf between Glencore management's expectations on price and what investors will be willing to pay.

Fund managers participated in the poll on condition of anonymity because of the possible impact their views might have on pricing the proposed initial public offer (IPO).

I don't think people really know how to value this business and I suspect maybe, the people at Glencore place quite a high value on (it) and that might be rather higher than the market is prepared to give, said a senior equities manager at a fund house running more than $700 billion in global assets.

There could be a fundamental problem there and an uncertain market won't help that, he added, noting that if the deal did not launch by May, it was unlikely to proceed before the final quarter of 2011.

Market volatility has already undermined other planned stock offerings, such as the attempted $2.8 billion IPO from Denmark's ISS, which was pulled on Thursday.

Other deals to stumble on market volatility include private equity firm Apollo Global Management LLC's $500 million U.S. IPO and a $189 billion sale by Chinese oil equipment manufacturer Hilong Holdings.

Some managers said they felt Glencore was determined to push on with its listing against market headwinds to raise much needed cash to pay off exiting partners, but the survey uncovered deeply held concerns about investment in Glencore.

A source close to the company said any IPO would be aimed at providing financial flexibility to grow the company further, rather than pay-out partners.

It's a business that's a bit like investment banking. It can generate stupendous returns when market conditions are favorable but that doesn't mean as a new investor I would be prepared to put a multiple of 12 times on future earnings, said one manager of a UK equities fund at a firm controlling more than $60 billion.

One manager pointed to a likely move to merge with mining company Xstrata -- in which Glencore is already the largest shareholder with a 34 percent stake -- as adding to the momentum behind management's desire to press on with an IPO.

I think they just want deeper capital markets access and the view in the market is that there will be a takeover or merger with Xstrata at some point, he said.

(Writing by Chris Vellacott, additional reporting by Cecilia Valente, editing by Alexander Smith)