Private equity firms Silver Lake Partners and Partners Group are set to write an equity cheque of around 600 million euros ($755 million) to back their 1-billion euro acquisition of tax-free shopping business Global Blue, banking sources said on Thursday.

The pair landed Global Blue from Equistone after beating rivals including Boston-based TH Lee Partners, BC Partners and EQT in an auction.

The buyout is likely to be backed by some 40 percent debt, but could be even lower than this at around 3.5 times the company's 97 million euro EBITDA, banking sources added.

Some bankers raised concerns over how much debt should back the buyout, questioning the sustainability of Global Blue's EBITDA before interest, taxes, amortisation and depreciation) which has trebled in the past two years, bankers said.

Given these concerns it would have been difficult to sell -on the loans in the wider market if the debt portion of the deal was higher, bankers said.

Silver Lake and Equistone confirmed the sale but declined to comment on financing.

An equity cheque of around 60 percent is much higher than touted on other auctions in the market.

The buyout of German bandages maker BSN Medical is expected to be backed by around 30 to 40 percent equity while the buyout of Europe's biggest frozen food company, Iglo, is expected to be backed by as little as 25 percent equity, bankers said.

Royal Bank of Canada, JP Morgan and Natixis have underwritten the debt on Global Blue which will be provided through all senior leveraged loans.

A bank meeting to syndicate the loans to the wider market will take place in June, bankers said.

Global Blue - which is headquartered in Nyon, Switzerland and helps overseas travellers into Europe reclaim VAT sales tax on their shopping - has benefited from Russian and Chinese shoppers attracted to Europe.

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