Adria's share capital has thus increased by EUR 1.5m to EUR 3.28m and its majority ownership has passed to Stefan Beulertz, until now the sole owner of STBE.
According to news portal Siol, STBE had bought Adria's brand from Adria a while ago for EUR 8m.
Before Beulertz became its majority owner, Adria was in sole ownership of AA International Aviation Holding, a company within the German turnaround fund 4K Invest, which bought Adria from the Slovenian state in 2016.
The airline said its strategy and day-to-day operations would not change under the new ownership. "The merger by acquisition of STBE is one of the measures to improve the company's financial strength and performance," Adria told the STA.
Struggling with liquidity issues, Adria was supplied with EUR 4m in fresh capital at the end of 2018.
Its owners announced another EUR 10m capital hike in the first quarter of this year and the move is believed to be a part of this operation.
Last year, Adria was scrutinised by the Civil Aviation Agency for speculation of insolvency, but the agency said last month the airline was able to secure long-term solvency, so it kept the air operator certificate.
Meanwhile, Finance cited an unofficial source saying the company had generated an operating loss of EUR 14-15m last year.
Adria neither confirmed nor denied the report, reiterating it would inject the airline with EUR 10m in fresh capital by the end of March.
Adria will phase out flights to Moscow and Düsseldorf this week and terminate cooperation with German airport Paderborn-Lippstadt.
"We have not managed to agree further conditions for air services under which we could carry on the cooperation [with Paderborn]… All the other operations of Adria Airways remain unchanged," the company told the STA.