Query: Who purchased the International Petroleum Exchange in 2001?
Context: Michael Greenberger specifically named the Atlanta-based IntercontinentalExchange, founded by Goldman Sachs, Morgan Stanley and BP as playing a key role in speculative run-up of oil futures prices traded off the regulated futures exchanges in London and New York. However, the IntercontinentalExchange (ICE) had been regulated by both European and U.S. authorities since its purchase of the International Petroleum Exchange in 2001. Mr Greenberger was later corrected on this matter.