The contract for the acquisition of DSME by South Korean rival Hyundai Heavy Industries (HHI) was signed on Friday amid protests in Seoul.
The deal sees Korea Development Bank (KDB) sell its majority holding of 55.7% in DSME, worth more than KRW 2trn ($1.78bn), to form a shipbuilding giant with a 20% share of the worldwide newbuilding market.
Hundreds of DSME union members clashed with riot police in front of KDB's headquarters as they attempted to storm the building to block the signing ceremony, according to Yonhap News Agency.