Following last year’s decline of almost 9%, enough to make it the worst of the nine sector SPDRs, the Energy Select Sector SPDR (NYSEArca: XLE), has rebounded in style in 2015.

XLE’s 4% year-to-date gain places it fourth among the nine SPDRs and the ETF recently got some welcomed news when its largest holding, Dow component Exxon Mobil (NYSE: XOM), the largest U.S. oil company, boosted its quarterly dividend to 73 cents per share from 69 cents.

XLE investors are now waiting on Chevron (NYSE: CVX), the ETF’s second-largest holding, to follow suit. Chevron usually announces a dividend increase in the second quarter, but resisted doing so when it reported first-quarter earnings last week. Exxon and Chevron combine for over 28% of XLE’s weight. [Exxon Dividend Increase Good for These ETFs]

Schlumberger (NYSE: SLB) and Kinder Morgan (NYSE: KMI), XLE’s third- and fourth-largest holdings, respectively, have also recently boosted payouts.

On a historical basis, the current month is often kind to XLE. Going back to 1999, the first full trading year for the nine sector SPDRs, XLE usually leads the way in May with an average gain of just over 1%, according to CXO Advisory. [Sector ETF Ideas for May]

Those are some cheery anecdotes, but investors should not expect a bump-free ride with oil equities and ETFs such as XLE. In the eyes of some analysts, there is at least one big “if” that will play a significant role in determining XLE’s fortunes.

“Profit expectations have fallen dramatically–though the pace slowed recently–which in turn has pushed the sector’s P/E ratio much higher even as stock prices have declined. Obviously momentum isn’t in the Energy sector’s favor, but stocks appear attractive in terms of valuation if–and this is a big if–the depressed profitability (Return on Equity) forecast for this year and next is temporary, rather than a ‘new normal’ reflecting abundant new supplies from shale,” said AltaVista Research in a new note.

The research firm rates XLE neutral, which “indicates that valuations adequately reflect the fundamentals of stocks” in the ETF.

Notably, AltaVista does not view XLE as a bargain on valuation. The research firm estimates the ETF’s 2015 price-to-earnings ratio to be 33.8 before falling to 23.9 next year. That is well above AltaVista’s estimated 2015 P/E for the S&P 500 of 17.5.

Investors have added $1.45 billion to XLE since the start of the second quarter.

Energy Select Sector SPDR