Stock Market Update

[BRIEFING.COM] The major averages are charting session lows, with the S&P 500 (-0.6%) and Nasdaq Composite (-0.6%) slipping beneath their 50-day moving averages. The indices have not closed beneath their 50-day moving averages since the market rebounded from April lows, making the figure a key technical support level. Both indices violated their 50-day moving averages on Friday before closing higher.  

While the DJIA (-0.6%) holds a similar loss, it has not yet dipped beneath its 50-day moving average in today's action (or Friday's for that matter). 

Participation has weakened after mixed strength this morning. Eight S&P 500 sectors trade lower, with the top-weighted information technology sector (-1.4%) at the bottom of the standings. NVIDIA (NVDA 186.07, -4.10, -2.16%) is under pressure ahead of its earnings release on Wednesday. 

The communication services sector (+1.8%), and in particular, Alphabet (GOOG 288.18, +11.20, +4.04%), is helping to mitigate further losses, with the tech giant trading sharply higher after Berkshire Hathaway Inc. (BRK-B 508.49, -0.45, -0.09%) revealed a new $4.9 billion position in the company. 

Even with Alphabet's gain, the Vanguard Mega Cap Growth ETF is down 0.6% as momentum names continue their recent unwind. 

Meanwhile, the Russell 2000 (-0.5%) and S&P Mid Cap 400 (-0.5%) hold similar losses.