Nvidia investor dilemma: how much is too much in a stock portfolio?

Outsized positions in artificial intelligence darling Nvidia (NVDA.O) have boosted portfolio managers’ returns this year but the bets stand to magnify risk if the chipmaker’s red-hot shares see a reversal of fortune.

Nvidia shares are up about 785 per cent since the start of 2023 and have risen some 160 per cent this year alone, boosted by demand for its chips, seen as the gold standard in the AI field. Nvidia briefly became the world’s most valuable company in June before a dip in its shares returned that title to Microsoft.