Notorious activist investor Elliott Management has taken up a £3.8bn stake in BP, becoming the ailing oil major’s third-largest shareholder, according to reports. The US fund’s investment in the London-listed petrochemical giant emerged last weekend,

BP's U.S.-listed shares are rising 6% Monday following reports that activist hedge fund Elliott Investment Management has amassed a stake in the British oil giant and is seeking to make changes.

Elliott is known for its aggressive activism in the companies it invests in, frequently pushing for rapid and significant change.