Within the sector, NextEra Energy Inc (NYSE: NEE) and NRG Energy Inc (NYSE: NRG) are among the two large stocks which topped this week's race, showing a sensational rating of 3.5% and 1.4%, respectively. Among utilities ETFs, one ETF following the sector is the Utilities Select Sector SPDR ETF (AMEX: XLU), which is up 0.3% on the day, and up 12.16% year-to-date. NextEra Energy Inc, on the other hand, is up 20.11% year-to-date, while NRG Energy Inc, is down by 3.74% year-to-date. Figures combined, NEE and NRG make up approximately 10.4% of the principal holdings of XLU top chart.

Meanwhile, the second top grossing sector is the Financial sector, losing just 0.1% of their stocks. Among large Financial stocks, Extra Space Storage Incorporated (NYSE: EXR) and Chubb Ltd (NYSE: CB) depict a stunning percentage of returns, showing a gain of 2.5% and 2.2%, respectively. One ETF closely tracking Financial stocks is the Financial Select Sector SPDR ETF (XLF), which is down 0.1% in midday trading, and up 2.85% on a year-to-date basis. Extra Space Storage Inc., meanwhile, is down 11.44% year-to-date, and Chubb Ltd is up 7.13% year-to-date. CB makes up approximately 2.4% of the underlying holdings of XLF.

Here's a shot of how the S&P 500 components within the various sectors are faring in afternoon trading on Friday. According to this chart, only the Utilities Sector gained returns while the other eight lost almost a per cent of their stocks.

The utilities sector is a category of stocks for utilities such as gas and power. The sector contains companies such as electric, gas and water firms, and integrated providers. Because utilities require significant infrastructure, these firms often carry large amounts of debt; with a high debt load, utilities companies become sensitive to changes in the interest rate.