PMC-Sierra (PMCS) was down 6.8% in early trading, as it and other communications chip makers struggled under the weight of Cisco's (CSCO) - Get Report earnings and outlook, coupled with an earnings warning from National Semiconductor (NSM) .

Vitesse Semiconductor


was down 7.4%,

TriQuint Semiconductor


was down 4.6% and

Applied Micro Circuits


was down 4.7%.