US chip stocks slide after Intel's forecast misses estimates

** US semiconductor shares fall in extended trading after Intel's forecast misses estimates on Israeli fab blast, PC weakness

** Intel INTC.O plunges ~16% to $77.24 after forecasting Q4 revenue of $15 billion to $16 billion, below analysts' estimate of $17.07 billion

** Nvidia NVDA.O, Advanced Micro Devices AMD.O, Marvell MRVL.O and Broadcom AVGO.O fall between 1% and 4%

** The Philadelphia SE Semiconductor Index .SOX had gained about 6.9% this week through Thursday's close

** Memory-chip maker Micron MU.O declines 2.3%, while data-storage co Western Digital WDC.O falls 1.9% after the bell

** As of last close, the index .SOX has jumped over 62% YTD