Exhibit 99.1 MPLX LP Reports First-Quarter 2024 Financial Results • First-quarter net income attributable to MPLX of $1.0 billion and net cash provided by operating activities of$1.3 billion • Adjusted EBITDA attributable to MPLX of $1.6 billion and distributable cash flow of$1.4 billion • Returned $951 million of capital to unitholders • Advanced growth strategy with processing plants in the Marcellus and Permian basins; Harmon Creek II in service and Preakness II approaching startup • Acquired partner's ...