Ltd said on Saturday that an application has been filed with the company National Company Law Tribunal (NCLT) for the merger of HDFC Investments Limited and HDFC Holdings Limited with HDFC Bank. This is part of a proposed merger of the country’s largest private sector bank by balance sheet with its parent, mortgage lender (HDFC Ltd).

HDFC said in a regulatory filing, a joint company scheme is subject to various statutory and regulatory approvals including NCLT, Competition Commission of India and the respective shareholders and creditors of the companies involved in the scheme.

HDFC Bank has already got in-principle approval Reserve Bank (RBI) for merger with HDFC Ltd., with other approvals.

The parent-subsidiary merger is seen as the biggest transaction in India’s corporate history.

In April this year, HDFC Bank and HDFC Ltd announced a merger proposal under which the bank will acquire the mortgage lender for approximately USD 40 billion in about 18 months.