Refiner stocks have rallied far beyond the broader market and are now trading at extreme valuations relative to historical patterns, suggesting the trade is overextended and vulnerable to mean reversion.

"Marathon Petroleum, Valero Energy and HF Sinclair have each surged more than 80% this year, compared with an approximately 11% gain for the S&P 500. The S&P 500 Oil & Gas Refining & Marketing Sub-Industry Index has jumped 104% this year and stood 41% above its 150-day moving average, a condition that has occurred only five other times in the index's history, with every previous instance followed by negative returns over the following six months averaging a 10.1% decline."