Some analysts and fund managers argue that U.S. markets may have more room to run as low volatility and high investment confidence help support the momentum. Moreover, Bond added that recent healthy economic data, along with strong earnings results, also suggested more growth ahead.

Leading the charge this week, the traditional safe-haven utilities and growth-heavy technology sectors have outperformed, with both S&P 500 sectors up more than 2% in the past week. Tech shares have surged this year and outperformed on improved earnings results while dividend-paying utilities climbed on diminished inflation expectations.

On the other hand, S&P 500 energy companies were among the laggards this week, falling off almost 2.2%, on weakening crude oil prices, despite promises from the Organization of Petroleum Exporting Countries to extend production cuts through next year.

For more information on the markets and U.S. Stock ETFs, visit our S&P 500 category.