Canada's Enbridge is buying Houston-based Spectra Energy for about $28 billion, creating North America's largest energy infrastructure company.
Both companies operate pipelines that deliver oil and natural gas.
Under the terms of the deal, Spectra Energy shareholders will receive 0.984 a share of the combined company, or about $40.33, for each Spectra Energy share they own. When the deal closes, which is expected to happen in the in the first quarter of 2017, Enbridge shareholders will own about 57 percent of the combined company and Spectra Energy shareholders will own about 43 percent.
Enbridge shares fell 1.8 percent to $40.25 before the stock market opened Tuesday. Shares of Spectra Energy Corp. rose 9.3 percent to $39.50.