However, with technology’s ascent and that of QQQ, come concerns that the Nasdaq-100 is too heavily exposed to a small number of stocks. Additionally, some analysts opine that the benchmark’s significant technology overweight leaves it vulnerable should tech stocks fall out of favor.

QQQ, one of the largest U.S. ETFs, has equal-weight equivalents equal-weight equivalents such as the Direxion NASDAQ-100 Equal Weighted Index Shares (NYSEArca: QQQE) and the First Trust NASDAQ-100 Equal Weighted Index Fund (NasdaqGS: QQEW).

QQQ “has been around since 1999, and in that time has become among the most liquid ETFs in the world, trading around 24 million shares a day, according to data compiled by Bloomberg,” reports the news agency.

Year-to-date, investors have added $2.68 billion to QQQ, double the total added by the next closest PowerShares ETF.

For more news and strategy on the Technology market, visit our Technology category.

Tom Lydon’s clients own shares of Apple, Facebook and QQQ.