NOL said in a statement it carried the equivalent of 159,100 40-foot containers on its ships in the period ended May 29, down from 201,700 a year earlier.
The average revenue from each container fell 23 percent to $2,326.
Singapore handled 20.3 percent fewer containers in May from a year ago but traffic edged up 0.7 percent from April, according to government data, showing actvity at the world's busiest container port may have stabilised but there is no recovery yet.