[The S&P 500 Index has its worst weekly performance since June. AI concerns hit chip stocks hard] October 17th, the S&P 500 Index fell on Friday and recorded its largest weekly decline since June. A surge in crude oil prices reignited inflation concerns, while worries about the sustainability of artificial intelligence trading weighed on chip stocks. The S&P 500 fell 1.1%, with shares in cloud computing services provider CoreWeave Inc. plunging, adding to a sell-off in technology stocks. The Nasdaq 100 index fell 2.5% on Friday. The index fell 5.5% this week, its worst weekly performance since April 2025. Adding to market concerns, Brent crude oil hit $110 a barrel for the first time since May. After two different indicators showed that U.S. inflation was higher than expected, rising oil prices intensified market concerns about price pressures. The energy sector rose 2.47% and became the best-performing sector of the S&P 500 Index on Friday.