The boxship merger between Korea's Sinokor Merchant Marine and Heung-A Shipping will be finalised in October.
A deal to unite their container shipping services was signed last week, according to the ministry of oceans and fisheries and the Korea Ocean Business Corp (KOBC) fund, the Maeil newspaper said.
The two companies had previously teamed up with compatriot HMM on intra-Asian containership services in 2017.
The current merger plan was agreed last year, with the idea of it being completed before the end of 2019.
Sinokor is described as the fourth biggest Korean liner company, with Heung-A at five.
Following the merger, they will have a capacity of 88,300 teu, number three in Korea and 19 on the global list.
Clarksons has Sinokor at number 20 worldwide currently.
The report said the two companies will start consolidating their container shipping services this week.
South-east Asian routes will be integrated first and then China/Japan services by the end of next year.