MUMBAI: India's Adani Enterprises, which is involved in coal mining and power generation, has launched a share sale to institutional investors to raise up to $850 million, sources with direct knowledge of the deal said on Tuesday.

The floor price of the sale is 536.15 rupees a share, a discount of about 1.5 percent to the stock's Tuesday closing price, said the sources, who did not want to be named as they were not authorised to speak to the media.

Shares in Adani Enterprises, which the market values at roughly $6 billion, ended 0.2 percent lower on Tuesday at 544.20 rupees in a Mumbai market that fell 0.3 percent.

The qualified institutional placement is worth $600 million, with an option to increase it by $250 million, according to a term sheet seen by Reuters. Earlier, sources had told Reuters the company could raise up to $750 million.

The issue will close on Wednesday. Adani Enterprises said in a document on its website on Tuesday that it plans to pursue "alliance opportunities" but did not say exactly how it intends to use the proceeds.

Australia's Linc Energy was in talks with Adani to sell a coal asset for $1 billion, a media report quoted Linc's chief executive as saying last week. Adani Enterprises is one of the largest commodity trading firms in India.

Its Adani Power unit, which last year raised $630 million in an IPO, is developing several thermal power projects in India. The Adani share sale is being managed by Citigroup, Bank of America Merrill Lynch, Morgan Stanley, UBS, IDFC Capital, Enam Securities, ICICI Securities, and Kotak Mahindra Capital.