The Globe and Mail reports in its Saturday edition that thematic exchange-traded funds have exploded in popularity over the last few years, as investors have piled into bets on AI, cleantech and cybersecurity. The Globe's Tim Shufelt writes that the problem is that they do not tend to perform very well. Morningstar's last study of the thematic universe showed that just 18 per cent of these funds survived and outperformed the market over the 12 months up to end of last June. Over the past 15 years, thematic ETFs globally had a failure rate of 91 per cent. That means fewer than one in 10 that were available at the start of that period survived and outperformed. The ETF wrapper makes it easy for fund providers to quickly seize on whatever is the flavour of the month, but fad investing has always existed, said Daniel Straus, head of ETFs for National Bank Financial. "Before ETFs, people would go and buy the most speculative single stocks in those areas," he said. "At least an ETF is diversified." Investors in the cannabis stock craze, for example, faced the real risk of a single-stock bet going to zero. Cannabis ETF performance, on the other hand, has been merely terrible. Sometimes a good story is a dangerous thing.