Buoyed by strong performances by the technology sector and the biotech industry, the Nasdaq Composite is up 4%, a gain that is more than six and a half times the S&P 500’s year-to-date.

That extends a lengthy run of out-performance by some Nasdaq ETFs over S&P 500 equivalents. For example, the PowerShares QQQ (NasdaqGM: QQQ), which tracks the Nasdaq-100, is up 72.2% over the past three years compared to a gain of just under 61% for S&P 500 tracking ETFs. Even that lengthy, stellar run for the Nasdaq, some market observers believe the time is still right to prefer an ETF such as QQQ over its S&P 500 rivals.

“Investors searching for opportunity in a high valuation market should look to the Nasdaq 100, supported by historically low relative valuation and impressive forward growth expectations. During the last 10 years, NDX has traded at an average P/E multiple 30% greater than the S&P 500, but it currently trades at just an 8% premium (18.8x vs. 17.5x),” said Goldman Sachs strategist David Kostin in a note posted by Ben Levisohn of Barron’s.

Increasing the allure of QQQ is the ETF’s evolution since coming to market in March 1999 at nearly the apex of the tech bubble. Although still tech-heavy (the sector accounts for almost 58% of the ETF’s weight), consumer discretionary and healthcare names combine for over 34% of QQQ’s weight.

There is another big change to the Nasdaq-100 that is helping investors: The tech sector’s rising dividend credibility. When QQQ debuted in March 1999, the ETF’s dividend yield was just 0.05%. That yield is now over 1%. [Nasdaq’s Evolution Good for ETFs]

At a weight of 14.8%, more than double the weight assigned to Microsoft (NasdaqGS: MSFT), Apple (NasdaqGS: AAPL) has been a key driver of QQQ’s recent bullishness. However, QQQ would still deliver superior earnings growth relative to the S&P 500 even if Apple departed. [Apple’s ETF Impact]

“Consensus expects Nasdaq 100 EPS to grow by 15% over the next 12 months compared with just 5% for S&P 500. Apple  is one – but not the only – reason for the attractive relative growth and value of NDX. Even when Apple is removed, NDX ex-Apple has superior sales and EPS growth although the P/E expands by one point,” according to Goldman.