Institutional ownership in PSX
Institutional ownership in Phillips 66 (PSX) currently stands at ~71.0%. It was ~69.0% in January 2017. Institutional ownership levels reflect the confidence level or sentiment that sophisticated market participants such as institutions have in a stock. Normally, everything else being equal, building institutional ownership implies a favorable opinion of a stock.
Institutional ownership for peers
Institutional ownerships for Valero Energy (VLO), Tesoro (TSO), and Marathon Petroleum (MPC) have risen ~2.0%, ~7.0%, and ~3.0%, respectively, since January 2017. Their current institutional ownerships stand at ~82.0%, ~95.0%, and ~83.0%, respectively. For refining sector stocks, you can consider the iShares Global Energy (IXC), which has a ~5.0% exposure to the sector.