An unprecedented trend appears to be underway between the booming energy sector and the turbulent stock market.

Over the past ten trading days, the Bespoke Investment Group's Paul Hickey finds energy has never performed this well while the S&P 500 is trading lower.

"The energy sector is up close to 17% and the S&P 500 is down," the independent research firm's co-founder told CNBC's "Trading Nation" on Tuesday. "This is an unheard of situation that we're in."

He highlights the relationship in a special chart with data going back to 1990.

"Part of the reason here is just because energy has become such an insignificant part of the entire S&P 500," said Hickey. "Its weighting is less than 3%. It's about half the weight of Apple."

In the short-run, Hickey calls energy "extremely overbought," pointing out the group is two standard deviations above the 50-day moving average. Meanwhile, he notes the S&P 500 is two standard deviations below its 50-day moving average.

"You have a big disparity where one end of the rubber band is stretched way to the left and the other is stretched way to the right," he noted. "When you've seen that happen, you tend to see a reversion to the mean."

He also mentions the Energy Select Sector SPDR Fund is up 3% in three of the last four trading days. It's a longer-term bullish trend, according to Hickey, that has happened only a few times in about the last two decades.

"Following prior periods of similar strength in XLE, the sector has seen short-term profit-taking, but a year later it was higher all five times," Hickey wrote to investors this week. "Performance of the broader equity market following similar surges in the Energy sector was uniformly weak in the short-term, but uniformly positive six and twelve months later."

On Tuesday, the XLE rose 0.58% to close at $55.04, and is up more than 13% over the past month.

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