Utilize the input text as a context reference, choose the right relationship between Glencore and London Stock Exchange 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.

That was before Glencore listed on the London Stock Exchange (Other OTC: LDNXF - news ) in May 2011 at 530p and then acquired mining giant Xstrata a year later.

Answer: stock_exchange