The stock, which slumped over 20 percent to all-time lows on Wednesday, recovered 8 percent in early trading on Thursday after the statement from the company's board.
It was also supported by a ban on short-selling in Portugal Telecom (PT) shares declared by the market regulator CMVM for Thursday.
Shareholders are required to approve a 7.4 billion euro sale of the Portuguese assets to telecoms group Altice.
The PT board said the meeting was going ahead, that it saw no reasons to postpone it and that only shareholders themselves could decide to suspend it.
It warned, however, that an approval of the sale by shareholders would mean forsaking the goal of the merger with Oi agreed last year, which aimed to a create a leading global operator with some 100 million clients.
PT SGPS is the largest single shareholder in Oi with a 25.6 percent stake. Oi now owns PT Portugal, the operating assets that belonged to PT SGPS before the merger. Oi has agreed to sell them to Altice, but the deal hinges on the approval of PT shareholders.