Detroit-based diversified DTE Energy Co. opened a public offering of 12 million equity units, the company said Sept. 28. The proceeds will be used to purchase midstream natural gas assets.

Each equity unit will be issued in a stated amount of $50 and will consist of a contract to purchase common stock and an undivided beneficial ownership interest in a remarketable $1,000 senior note.

The underwriters will likely receive an option to purchase 1.5 million additional units to cover overallotments.

Wells Fargo Securities, Citigroup and J.P. Morgan are joint book-running managers.