Consol Energy Inc and Noble Energy Inc said on Thursday they would form a master limited partnership (MLP) for pipeline operations they control in Pennsylvania’s Marcellus shale region.

Both companies have confidentially filed paperwork for the MLP to launch an initial public offering, which they hope will take place by the end of the year.

MLPs have been hugely popular among investors seeking higher yields, even though the structures often have corporate governance standards weaker than those of corporations.