X0306 4 2014-01-31 0 0001166036 MARKWEST ENERGY PARTNERS L P MWE 0001270065 SEMPLE FRANK M C/O MARKWEST ENGERGY PARTNERS, L.P. 1515 ARAPAHOE ST. TWR 1, STE 1600 DENVER CO 80202 1 1 0 0 Chairman, President & CEO Common Units 2014-01-31 4 F 0 36696 70.19 D 239359 D Common Units 150745 I Frank M Semple Revocable Trust Common Units 102000 I Robin Y Semple 2012 Dynasty Trust Common Units 94000 I Frank M Semple Dynasty Trust Common Units 44750 I EK Holdings LLC Amount of securities beneficially owned following the reported transaction(s) includes Common Units owned and Restricted Units subject to varying vesting terms. /s/ Sean M. McKendry as POA for Frank M. Semple 2014-02-04