For today’s investor, making money in markets may seem straightforward: put your money into a passive fund that tracks US stocks. It’s been a winning strategy for so long that it feels like the obvious choice. Yet as Merryn Somerset Webb, John Stepek and their expert guests discuss over the course of this four-part series, past performance is no guarantee of future returns, with major implications for how investors build their portfolios.

In the first episode, they examine how passive investing went from a niche strategy to the default for many people, channeling ever more capital into US stocks and the tech giants that dominate the market. Passive investing is still an investment decision, after all — one that leaves many investors with far more concentration risk than they realize.