The container shipping industry is to face another period of upheaval with the recent spate of mergers and possible consolidation among top carriers which is threatening to disrupt mega alliances even as the lines settle into their relatively new vessel tie-ups.

Last week, Neptune Orient Lines', owner of APL, confirmed in a Singapore Stock Exchange filing that it is in preliminary merger talks with CMA CGM and Maersk Line. This followed after the largely assumed merger of China Container Shipping Lines and Cosco was confirmed by U.S. Federal Maritime Commissioner William Doyle.

For shippers already frustrated with poor reliability, the prospect of more volatility from the mergers themselves and the inevitable restructuring of major shipping alliances that became operational this year is hardly appetizing. Nor, is the long-term prospect of higher rates provided by a smaller pool of players, the IHS Media report.

A partner in 10XOceanSolutions Inc., Chas Deller, which advises shippers in their carrier relationships, said that routing and terminals may change. Performance guarantees provided by one carrier to a shipper could also be questioned.

Timing will be key, with carriers hoping the new marriage or marriages can be leveraged before negotiations of trans-Pacific 2016-17 contracts at the end of April. 

A merged Maersk and APL, for example, would be the dominant mover of goods from Asia to the United States, with a 6.9 per cent market share, according to a PIERS analysis of each carrier's market share in the first nine months of this year.

The merger of CMA CGM and APL would give the combined entity a 6.8 per cent share on the trade lane, while a combined CSCL and Cosco would control 6.07 percent of the trade, according to PIERS, a sister product within IHS.

If consolidation occurs, "we have reached the next level of uncertainty in global ocean shipping," Mr Deller said.

If the changes were made, the new alliance structure would be: 2M (Maersk, MSC); G6 (OOCL, Hapag-Lloyd, NYK, Hyundai, MOL, Hamburg Sud); KYHE ("K" Line, Yang Ming, Evergreen, Hanjin); and 05 (CMA CGM, CSCL, UASC, APL, Cosco).

Two factors are spurring carriers to scramble for potential partners. Carriers see major consolidation on the horizon and want to make sure they have the size needed to stay competitive at a time when scale increasingly matters. The other driver of consolidation is that there's no short-term relief of overcapacity that is pushing down freight rates.

Drewry warned last month that the industry faced three more years of overcapacity and things will get worse next year when 1.3 million TEU of capacity hits the water.

An additional 1.6 million TEU of new capacity was being added to the fleet this year, equating to a growth rate of 7.7 per cent.

This has pushed Drewry's Global Supply/Demand Index - a measure of the relative balance of vessel capacity and cargo demand in the market where 100 equals equilibrium - down to a reading of 91 in 2015, its lowest level since the recession-ravaged year of 2009.