Tech-driven losses in Asia came before European and US markets mostly traded lower."Fragile sentiment is leading to a continued pullback in memory chip stocks after their gravity-defying run as investors fret about elevated valuations," noted Dan Coatsworth, head of markets at AJ Bell trading group.Leading Wall Street equity indices pulled back, led by the tech-rich Nasdaq, which lost 1.5 percent.Seoul's Kospi fell more than six percent as chip titan SK hynix and Samsung both fell significantly amid growing anxiety that the AI rally -- which had pushed both firms to record highs this year -- had run its course.Traders are questioning whether the vast sums pumped into the AI sector in recent years will eventually pay off and justify the eye-watering valuations for some firms.Shares in TSMC fell in New York, even as the Taiwanese chipmaker issued positive forward guidance and announced that net profit soared more than 77 percent to a record high in the second quarter thanks to massive demand for AI hardware. It said it would invest an additional $100 billion in the US state of Arizona.Shares in Dutch firm ASML, which manufactures chip-making machines that underpin the tech industry, also fell after releasing blockbuster earnings on Wednesday."This all makes one wonder what US tech corporations will have to come up with to get investors genuinely excited again," said market analyst David Morrison at Trade Nation."This is important, as the earnings season picks up several gears over the next fortnight."US retail sales ticked up by 0.2 percent month-on-month in line with analysts' expectations, but the increase was slower than the 1.0 percent jump in May.Analysts said the figures suggested solid underlying consumer demand given the drop in gasoline prices during the month.In spite of encouraging economic data, US stocks have been volatile this week, pressured not only by AI valuation doubts but also by worsening US-Iran tensions that have lifted oil prices most of the week."Higher oil is also increasingly testing the consensus view that peak cost pressures are behind us," said Jose Torres, senior economist at Interactive Brokers.Oil prices fell marginally Thursday as the US struck Iran and Tehran hit back at US allies in the Gulf on Thursday.Analysts at Rystad Energy lifted the odds that no "substantive agreement" emerges between the two countries to 55 percent.While the United States and Iran "have strong economic incentives to avoid a complete breakdown," there remain disagreements on Iran's nuclear program and the Strait of Hormuz, said Rystad senior vice president Jorge Leon."After Aug. 16, the question becomes whether the shipping market can adapt to a continuing threat rather than whether diplomacy can resolve one," Leon said.Key figures around 2020 GMTBrent North Sea Crude: DOWN 0.9 percent at $84.23 a barrelWest Texas Intermediate: DOWN 0.9 percent at $78.95 a barrelNew York - Dow: DOWN 0.2 percent at 52,552.97 (close)New York - S&P 500: DOWN 0.5 percent at 7,533.77 (close)New York - Nasdaq Composite: DOWN 1.5 percent at 25,881.95 (close)London - FTSE 100: UP 0.5 percent at 10,572.24 (close)Paris - CAC 40: DOWN 0.1 percent at 8,377.86 (close)Frankfurt - DAX: DOWN 0.3 percent at 24,915.49 (close)Tokyo - Nikkei 225: DOWN 2.8 percent at 66,835.54 (close)Seoul - Kospi: DOWN 6.4 percent at 6,820.60 (close)Hong Kong - Hang Seng Index: UP 1.3 percent at 25,008.60 (close)Shanghai - Composite: DOWN 1.9 percent at 3,882.41 (close)Euro/dollar: DOWN at $1.1436 from $1.1463 on WednesdayPound/dollar: DOWN at $1.3468 from $1.3554Dollar/yen: UP at 162.42 yen from 162.19 yenEuro/pound: UP at 84.91 pence from 84.66 pence