Shares in TeliaSonera fell back 7 kronor, or 11.3 percent, to 55 kronor on Wednesday morning.
On Tuesday the company reported a 7.7 percent rise in first-quarter net profit.
Net sales increased by 3.4 percent to 22.72 billion kronor.
“I am satisfied with the top-line growth and the bottom line but I am concerned about the margin within Broadband Services. Therefore further efficiency measures are needed in addition to the ongoing programs to
continue addressing the migration from traditional services,”said CEO Anders Igel in a statement.
“I am particularly happy with the usage increase in mobility and that our market initiatives in broadband are having an effect,” he added.