Oil prices are bouncing back from a three-year slump, but investors in energy companies seem to have missed the memo.

International crude prices have risen by more than 10% in the last year as production cuts by major suppliers helped shrink the market’s three-year-old glut. But energy equities have barely gained over the same period—an unusual divergence for sectors that are normally highly correlated. Investors have also put less money in energy equity funds.

Behind the lagged performance of equities is a cocktail of factors, analysts say, including companies’ high debt levels and a dearth of new investment that is hitting the bottom lines of oil services firms.

However, a more fundamental reason appears to be investors’ broad disillusionment with a sector that has endured wild price swings and is adapting to a new, lower-price environment.