PremiumThe risk of market "tantrums" is rising as sharp swings in semiconductor stocks force some investors to cut allocations, according to JPMorgan strategists.The team led by Nikolaos Panigirtzoglou wrote in a must-read note (available here to pro subs) a rebound in chip stocks to record highs this week has been accompanied by higher volatility, potentially triggering so-called 'VaR shocks' for portfolios.