AAS I said it was a joint venture, technically you could say Gazprom owns it since they control 51%, but Western companies provided half of the financing and owned the other 49%.
“Gazprom paid half the cost of building Nord Stream 2, with the remainder of the $11 billion pipeline project financed by British oil and gas major Shell (SHEL.L), Austria’s OMV (OMVV.VI), France’s Engie and Germany’s Uniper (UN01.DE) and Wintershall DEA (WINT.UL).”