Whether you love it or hate it, the PowerShares QQQ ( QQQQ) is one of the most highly monitored and frequently traded ETFs in the market today. This benchmark ETF tracks the capitalization-based Nasdaq 100 Index and is composed of the largest domestic and international non-financial companies listed on the Nasdaq. While QQQQ has a high correlation with other large-cap growth ETFs, like the iShares S&P 500 Growth Index ( IVW) and Vanguard Growth ETF ( VUG), key differences have helped QQQQ emerge as one of the most popular ETFs in the market today. To call the QQQQ "tech heavy" is an understatement. According to issuer PowerShares, the QQQQ has a 62.99% tech allocation. The second and third largest sectors in the QQQQ are health care and consumer discretionary, comprising 16.56% and 12.59% of the fund, respectively. QQQQ's top 10 holdings make up more than 45% of the fund, with prime holding Apple ( AAPL) comprising 13.21%. This top-heavy structure makes QQQQ particularly vulnerable to the movements of its top components. Top holdings can serve as a buoy or an anchor depending on the day's news. QQQQ's tech-heavy nature is revealed in a quick perusal of the top 10 holdings, eight of which are technology stocks: Apple, Qualcomm ( QCOM), Microsoft ( MSFT), Google ( GOOG) ( GOOG), Research In Motion ( RIMM), Oracle ( ORCL), Cisco ( CSCO) and Intel ( INTC) fall under the technology sector. The remaining two components are healt care stocks: Gilead ( GILD) and Teva Pharmaceutical ( TEVA). In addition, QQQQ offers traders a multitude of trading strategies to enhance their portfolios. The QQQQ options are among the top four most actively traded options on the CBOE.