Utilize the input text as a context reference, choose the right relationship between Steve Ballmer and Microsoft from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

Twitter rose 4.8 per cent to $US31.15 after Bloomberg reported that former Microsoft chief executive Steve Ballmer owns a 4 per cent stake in the company.

Answer: owner_of