...- EQM Midstream Partners L.P. recently delayed the expected in-service date for the Mountain Valley Pipeline (MVP) project and reported a higher total project cost estimate, which we believe will stress its credit metrics in 2021 given the project's importance to its deleveraging plan. - We also recently upgraded its main counterparty EQT Corp. to '##', which supports our view of the company's counterparty risk exposure. - We are affirming our '##-' issuer credit rating on EQM and our '##-' issue-level rating on its senior unsecured debt. Our '3' recovery rating (rounded estimate: 50%) on this debt remains unchanged. - The stable outlook incorporates our view that the MVP project will remain under construction through 2021, leading EQM's leverage to remain above 5.5x for the next 12 months. Our base-case assumptions include relatively stable volumes and EBITDA and deleveraging related to the MVP project, which we assume will enter service around year end 2021....