Wall Street darling Apple (NasdaqGS: AAPL) has been volatile since reporting blowout quarterly earnings and traders are watching closely to see if the stock can hold at its 50-day moving average, a key technical indicator.

Apple is the largest holding in PowerShares QQQ (NasdaqGM: QQQ), the tech-heavy exchange traded fund that is a favorite among traders. The ETF has rallied since climbing above its own 50-day average last month.

The fund, which tracks the Nasdaq-100 Index, was up 8.4% year to date through April 29, in line with the S&P 500, according to Morningstar.

PowerShares QQQ ended Monday’s session slightly negative as key components Apple and Microsoft (NasdaqGS: MSFT) both lost about 1%. [Apple, Microsoft Tilt Nasdaq ETF Into the Red.]