May 7 : Arm shares tumbled on Thursday after the company warned of smartphone market softness and challenges in securing supply for its new artificial intelligence chip to meet growing demand. The stock fell 5 per cent to $225.43, with the drop set to erase more than $12 billion from the company's market valuation of $252 billion. The British chip designer's shares have more than doubled in value this year, outperforming other chip majors. Arm has doubled down on its AI push this year with a