A "clear sign" of trouble, says Paris research house, is the fall of the Shanghai spot rate that has recorded six consecutive weeks of declines, despite strong peak season demand.
Carriers in August and September failed to push rate increases through, something Alphaliner said was evidence of rate cutting starting to take hold.
Analysts at Alphaliner note that it has taken a year to fully clear out the tonnage of the bankrupted Korean carrier Hanjin Shipping.
Only a single vessel formerly operated by Hanjin remains idle: the 1,647-TEU Orion, owned by Alpha Ship.
"The rapid depletion of the idle fleet since April and continued deliveries of 14,000 to 21,000-TEU ships have added over one million TEU to the global fleet in the last year.
While strong cargo demand has kept fleet utilisation levels at above 90 per cent on most headhaul routes this year, the onset of the slack winter season from October is expected to put pressure on rates, Alphaliner warned.
"The rate truce that carriers have largely abided by since Hanjin's sudden exit one year ago, now appears to be crumbling. Rate slashing just ahead of the October holidays in China points to further rate instability as carriers continue to jostle for market share," said the report.