Index tracking accounts for around one-third of the total US mutual fund market and is still growing rapidly. However, this author argues that the economic environment we are entering will be unsuited to indextracking strategies. Jensen identifies six structural megatrends that are set to disrupt investors around the globe, including: the end of the debt supercycle, retirement of baby boomers, declining spending power of the middle classes, the rise of the East, the death of fossil fuels, and mean-reversion of the wealth-to-GDP ratio. The author holds that these six themes have the potential to create conditions that will result in low economic growth for decades to come. Investment techniques and methodologies, including passive investing strategies, that have worked well in the bull market of the last 35 years will no longer deliver acceptable results. This author calls for a new investment approach and warns of the future decline of index tracking.