Nvidia's (NVDA) splashy new gaming chip unveil wasn't enough Monday to curtail the ongoing blood-letting in semiconductor stocks. 

Semis continued to lag on Monday amid concerns about weakening Apple (AAPL) iPhone sales, with 24 of the Philadelphia Semiconductor Index's 30 components falling. Declines were paced by Western Digital (WDC) and Intel (INTC) . Nvidia shares reversed course mid-day as CEO Jensen Huang took the wraps off powerful new gaming chips.

The SOX, as it's called on Wall Street, is now trading below its 50-day, 100-day and 200-day moving averages. 

Semiconductors face a case of the Mondays:
$NVDA -1.9%
$WDC -1.7%
$INTC -1.7%
$AVGO -1.3%
$LRCX -1.1%
$AMAT -1%
$NXPI -0.9%
$NXPI -0.9%
$TXN -0.8%,
$AMD -0.6%

— TheStreet (@TheStreet) August 20, 2018

The SOX has under-performed the red-hot Nasdaq Composite since mid-June. On Aug. 10, the SOX Index slipped below the key 50-day moving average for the first time since late July amid a broader market pullback.

For some on Wall Street, the lagging chip stocks -- notably high-profile names such as Intel and Micron ( MU)  -- is a red flag on the overall market's rally. Remember, chip companies are often viewed as a leading indicator on global demand as their products are required early on in the production process.
What Jim Cramer is saying about Nvdia and Apple.