[FAP] Oneok agrees to buy Magellan for $18.8 billion will create one of the largest pipeline operators in the United States. Oneok Inc. Agreed to buy Magellan Midstream Partners LP for $18.8 billion in cash and stock, which will create one of the largest oil and gas pipeline operators in the United States. Each share held by Magellan shareholders will receive $25 in cash and 0.6670 Oneok shares, a 22 per cent premium to Magellan's closing price on May 12, the two companies said in a joint statement on Sunday.