The challenge of finding attractively priced assets in a sector brimming with hype is another reason why some thematic investors may prefer to put their trust in a professional fund manager.

However, actively run vehicles also face difficulties finding value in industries widely expected to flourish, particularly if they arrive late to the party. 

Should the fund manager be under pressure to fulfill a strict mandate of pursuing specific stocks linked to a certain theme, there’s a good chance he or she will be forced to buy into all the hype -- and risk being blinded by it.

“All too often, if a fund is launching on a ‘theme’ it could well be because the marketing department sees it as one which will attract a good deal of money,” says chartered financial planner Philip Milton. “Usually that is because the sector/segment, etc, has been too well supported.”

Then again, the entire stock market is currently dominated by full valuations and high volatility. Provided you pick the right theme and fund, and have enough belief in them to stick around for the long-term, you may just be in luck.

Daniel Liberto is a freelance financial journalist