The revised deal between ETE and Southern Union is for $8.9 billion, including $5.1 billion in cash and common units.
Last week, Williams offered Southern Union $8.7 billion in cash, which outdid a previous $7.9 billion deal struck by ETE and Southern earlier this summer.
Under the terms of the revised agreement, which has been unanimously approved by the boards of both companies, Southern Union shareholders can elect to exchange their common shares for $40 in cash or 0.903
