| 1 | MAPX | Semgroup LP | added 4/2005; 7/2005 | | NAKINA |
| 2 | MAPX | Williams Energy Ventures, Inc. | added 10/1999; 7/2000; eliminated 4/2005 | | NAKINA |
| 3 | MAPX | Mapco Petroleum, Inc. | added 10/1993; 1/1994; eliminated 10/1999 | | NAKINA |
| 4 | MAPX | Mapco Gas Products, Inc. | eliminated 10/1993 | | NAKINA |
| 5 | MAPX | Mapco Petroleum, Inc. | added 4/1985 | | NAKINA |
| 6 | MAPX | Mapco Products Co. | added 10/1980; eliminated 4/1985 | | NAKINA |
| 7 | MAPX | Mapco Products Co. | added 10/80; eliminated 4/85 | | NRHS |
| 8 | MAPX | Mapco Petroleum, Inc. | added 4/85 | | NRHS |
| 9 | MAPX | Mapco Gas Products, Inc. | eliminated 10/93 | | NRHS |
| 10 | MAPX | Mapco Petroleum, Inc. | added 10/93; 1/94; eliminated 10/99 | | NRHS |
| 11 | MAPX | Williams Energy Ventures, Inc. | added 10/99; 7/2000 | | NRHS |
| 12 | MAPX | SEMGROUP LP [WILLIAMS ENERGY VENTURES; MAPCO PETROLEUM; MAPCO GAS PRODUCTS; MAPCO PRODUCTS CO.] | | | PWRC |
| 13 | MAPX | MAPCO Products | | | RSRV |
| 14 | MAPX | SEMGROUP LP | | | SCAC4 |