Investors with exposure to artificial intelligence and weight loss drugs have done well in recent years. Stocks like Nvidia and Novo Nordisk have skyrocketed and now comprise a far larger percentage of portfolios. Too much of a good thing is a problem, however, reducing diversification and introducing concentration risk.

It was two decades ago that Nvidia replaced Enron in the S&P 500. Since then, Nvidia’s shares have collapsed by more than 50 per cent three times.