Just one week ago, Nvidia became the world's most valuable company.The chipmaker - whose shares had risen nine-fold since the end of 2022 - overtook Microsoft as its stock market valuation reached $3.34trn. Since then, the shares have fallen by 13$500bn from Nvidia's stock market valuation reached when, last Thursday, the shares hit an all-time intra-day high of $140.76 each (taking into account the 10-for-one sha ...