Adani Enterprises of India increased 2% in early trade on Tuesday, the last day of its $2.5 billion secondary share sale, with all eyes on whether the company can secure enough backing for the offering after a scathing attack by a U.S. short-seller.

Billionaire Gautam Adani's group firms have lost $65 billion in stock market value since Hindenburg Research's January 24 report flagged concerns about the group's high debt levels and its suspected improper use of tax havens. Adani has called the report baseless.

A successful completion of the share sale will show investors still believe in the group's prospects and that it can weather the unprecedented short-seller challenge and its aftermath.

Adani Enterprises stock opened at 2,932 rupees, still below the lower end of the share sale's price band of 3,112 rupees.

The issue was subscribed 3% by Monday. The anchor portion of the issue - that accounted for 30% - closed last week with investments from investors such as Abu Dhabi Investment Authority.

Abu Dhabi conglomerate International Holding Company said late on Monday it will invest $400 million in the issue, but the bid has not yet been reflected in the data on Indian exchanges.

The share sale needs at least 90% subscription to go through.

Some other group stocks, including Adani Power, Adani Green and Adani Total Gas, were down 5%-10%.

Adani Wilmar was down 5%, but Adani Ports and Special Economic Zone rose 0.5% at open.