The NASDAQ 100 is a market weighted index and as such the top holdings are highly concentrated. In fact 56% of the total holdings are in the top ten positions.
Apple (AAPL) is a whopping 18% of the weighting and why there is some much movement of the index when Apple gains and falls.
Over the past month, the index (QQQ is the ETF) has risen 4.29%, even with Apple pulling it down by close to 0.60%. Not bad.
If Apple starts to pick up again, this could be a place to look for some upside into the end of the year.