In a transaction valued at $18.8 billion, Tulsa-based Oneok has acquired Magellan Midstream Partners to form a combined company with a total enterprise value of $60 billion. In a joint release, the companies said Oneok will acquire all outstanding units of Magellan in a cash-and-stock transaction including assumed debt. Magellan then will be merged into a newly formed 100% wholly owned subsidia...