Who owns space junk? There are several old satellites and rocket (second stage?) that get pushed to an orbit where they won't bother anything. Are these technically still owned by anyone (company or governments)? Thanks
This article from the Financial Times has this summary of the Outer Space Treaty:
Any debris created by satellites by technology failure or collision are the responsibility of the government where the satellite originated.
I think it is referencing this exact line from the Treaty:
States Parties to the Treaty shall bear international responsibility for national activities in outer space, including the moon and other celestial bodies, whether such activities are carried on by governmental agencies or by non-governmental entities, and for assuring that national activities are carried out in conformity with the provisions set forth in the present Treaty.
So technically the satellite, whether working or not, is the reponsibilty of the respective state government. The Department of Defence's Space Surveillance Network keeps track of all space debris larger than 5cm, so most companies will not continue to track their own spacecraft once it falls into disuse.
As such, it appears that if a foreign state wanted to clean/retrieve up a satellite/stage launched by a company in the US, it would need NASA's approval beyond that of the company itself, and NASA would be obliged to make sure nothing goes wrong.
Given the extra burden this places on NASA, one can imagine they would authorise only the most capable cleanup operations where the possibility of causing additional debris would be minimised.
-- EDIT --
Concerning ownership explicitely, rather than responsibility, this is already a tricky legal topic, with a number of papers written on the subject. These boil down to effectively trying to parse sections of the Outer Space Treaty, combined with existing cases of it happening.
In short, there is no existing legal framework for transfer of ownership of things in orbit. This hasn't stopped it from happening (the paper above gives a number of examples), but there is no formal mechanism. Pertaining to this question, that means that unless a lengthy legal procedure goes ahead, ownership of satellites is not transferred at End of Life (EOL), and remains with whatever entity owned it to begin with.
Article VIII of the 1967 Outer Space Treaty provides the answer. Slightly paraphrasing, the presence of objects in outer space does not affect the ownership of space objects "AND THEIR COMPONENT PARTS". So the black-letter legal answer is that the original owners still own them.
Whether or not this is a good idea is a separate question. But it is interesting to note that when active debris removal issues come up internationally, Russia - which owns many of the largest inactive space objects (upper stages mostly) - always reminds everyone that they still own their objects.