The final prospectus is due for completion by early August.
Romania, through the Economy Ministry, holds 20.6% in Petrom and estimates it will obtain around EUR552 million from selling a 9.84% stake.
The authorities in Bucharest selected a consortium led by Renaissance Capital to broker the deal.
Austria’s OMV, majority owner in Petrom, said last month it wouldn’t participate in the secondary public offering in the company.
As a 51% owner of OMV Petrom S.A., OMV has already control of the company and an increase in the stake would therefore not change the level of influence in decision-making, the Austrian company said.
Wednesday, Petrom’s shares closed up 0.27% at RON0.4081 in Bucharest. (EUR1=RON4.1184)