MPLX LP sold 17.3 million units at $22 each, above the expected range of $19 to $21, which suggested strong demand for the company. The banks managing the IPO may buy another 2.6 million shares.
Public shareholders will have a 23 percent limited partner interest in MPLX, while Marathon will own the rest. Marathon Petroleum, which separated from Marathon Oil Corp. in July 2011, refines oil and transports it. It formed MPLX recently to operate pipelines.
Trading under the "MPLX" symbol, units rose 23.6 percent to close at $27.20 Friday. Marathon Petroleum shares rose 3 percent to $55.61.
(Copyright 2012 by The Associated Press. All Rights Reserved.)