If the discussions are successful, the purchase of the banking unit Banco Espirito Santo de Investimento (BESI) would be Haitong’s first acquisition made outside China and Hong Kong.
The parties have not disclosed the financial terms of the deal.
According to local media reports, BESI is valued at around €400m ($493m).
BES, which was earlier claimed to be the biggest lender in Portugal in terms of market value, was bailed out in August 2014.
At that time, it was ordered by regulators to raise more funds following the disclosure of potential losses on loans to its parent company.
During the first half of 2014, BESI reported a net profit of €3m, while its parent firm posted a net loss of €3.6bn euros in the same period.
