Semiconductor stocks opened the third quarter on a weak note on Thursday, with several of the biggest winners from the AI rally witnessing sharp profit booking after a record-breaking run in the April-June period. The VanEck Semiconductor ETF (SMH), which tracks major chip stocks, fell more than 5%, a day after ending its strongest quarter on record. The index had surged 71% between April and June as investors aggressively bought companies expected to benefit from the artificial intelligence boom.Memory chip maker Micron led the losses, tumbling 11%, while Intel fell 9% and Advanced Micro Devices (AMD) declined 7%.The three companies together had added nearly $2 trillion in market value during the second quarter as investors broadened their AI bets beyond Nvidia, expecting rising demand for memory chips and central processors to support future growth.Selling pressure also spread to semiconductor equipment makers. Lam Research, KLA Corp. and Applied Materials, all of which more than dou...