The U.S. Energy sector appears to be another lucrative opportunity to invest in 2013. It is a sector with strong fundamentals and low valuations. Also, energy stands to gain from profits from abroad (3 Energy ETFs for America's Production Boom).

If the market continues with its recent rally, the energy sector is certain to be a beneficiary. With the boost in oil production capacity by most drillers, the U.S. will once again become a leader in energy development.

To play this optimism in the sector, XLE can prove to be a good investing tool providing access to 45 energy companies with a heavy reliance on the top ten holdings for performance. The fund has nearly 65% of its asset base of $7.2 billion in the top ten holdings.

The fund has been a laggard for the most part of fiscal 2012 ending the year with a gain of 5.21%. But since the beginning of 2013, the performance has been remarkably good with year-to-date returns of 5.69%.

Among individual holdings, the top two companies, Exxon Mobil and Chevron Corp, take away the major chunk of the asset base with a total combined allocation of 33.63%. The fund charges a fee of 18 basis points annually.