SPY vs QQQ ... likely more selling ahead

The major indexes often move in tandem with one another. Today the SPY along with several other indexes broke below the 50dma on heavy volume. The NASDAQ (QQQ displayed here) has been the strongest of the indexes for the bulk of this uptrend. Today it sliced below its 21ema for the first time in about a month. It looks poised to test the 50dma within the next day or two. That will likely send the other indexes lower along with it.