Trouble in the tanker market and impairments on some of its older vessels dragged Russian shipping giant Sovcomflot into the red in the first half of 2018.

Struggles in one half of the business contrasted with its performance in the industrial shipping segment, where fleet growth and long-term contracts continue to drive strong results.

Nikolay Kolesnikov, chief financial officer of Sovcomflot, noted the company was operationally profitable in the second quarter, with much of the loss carried...