Tech concentration hits dotcom-era extremes; UBS urges portfolio rebalancing Proactive uses images sourced from Shutterstock
The top ten US technology stocks now account for nearly 40% of the S&P 500’s total market capitalisation, marking the highest concentration since the late 1990s tech bubble and well above the 25% recorded during the dotcom crash itself.
That figure underscores how completely artificial intelligence has reshaped equity market dynamics. Microsoft, Apple, NVIDIA, Amazon, Alphabet and Meta have become index engines in their own right, with NVIDIA alone crossing the five trillion dollar market cap threshold.
The rest of the market, particularly non-tech and non-US sectors, has lagged substantially.
History offers cautionary tales. The Nifty Fifty era of the 1970s saw investors crowd into a handful of blue-chip growth stocks, eventually triggering years of stagnation.
The dotcom boom was even more extreme, with tech stocks reaching absurd valuations before the inevitable correction arrived. Late-1980s Japan saw market concentration in banks, and a few core sectors culminated in painful corrections and prolonged malaise. In each case, concentration and excessive valuations preceded sharp reversals.
UBS’s Chief Investment Office has taken a notably pragmatic stance. The bank remains constructive on global equities medium-term, but it has downgraded European IT to Neutral, citing 40% year-to-date gains and price-to-earnings valuations matching dotcom bubble highs. That is less a doomsayer’s pronouncement than a rebalancing signal.
The strategists argue that periods of tech strength should be viewed as opportunities to reduce excessive concentration rather than add to it. The practical recommendation involves broadening exposure across three dimensions.
Beyond the megacap leaders into lesser-known names; across sectors outside technology; and within the AI theme itself, stretching into infrastructure, industrials, automation and power supply chains where adoption is expanding.
Taiwan Semiconductor Manufacturing’s 30% May sales rise underscores continued capex cycle momentum, supporting medium-term constructiveness.
Yet portfolio construction matters. Investors sitting on concentrated megacap tech positions face a clear tactical choice: either rebalance during strength or accept the structural risks that historical patterns suggest accompany extreme concentration. UBS is effectively counselling the former.