TSMC-Fueled AI Rally Turns Taiwan Into a Global Leverage Hub

Taiwan's stock market has more than doubled over the past year, and according to Bloomberg, a striking share of that rally is sitting on borrowed money. Margin loans at Taiwanese securities firms have risen 160% over the past twelve months, approaching levels last seen just before the dot-com bubble burst in 2000. Total margin borrowing has surpassed $13 billion, a threshold the market has not crossed since September 2000.

The single stock at the center of this is TSMC, which now accounts for more than 40% of Taiwan's benchmark index and whose shares have more than doubled over the past year. That concentration has been enough to push Taiwan's total listed-company market capitalization up roughly 50% in 2026 alone, to approximately $4.95 trillion, overtaking the United Kingdom, Canada, and India in global rankings to place fifth in the world.

The velocity is striking at the daily level too. Around late May and early June 2026, margin debt reportedly spiked by NT$21.3 billion, roughly $680 million, in a single session. Investor defaults on stock trades reached over NT$2 billion in June 2026, the highest monthly level since 2019. Several brokerages including KGI Securities, Fubon Securities, SinoPac Securities, and Cathay Securities have responded by tightening lending conditions for certain stocks and imposing stricter loan limits.

The honest caveat is that a structural setup resembling a prior bubble is not the same as a prediction of when one pops. What the reporting does not give you is clarity on how much of that margin is concentrated in TSMC specifically, what share price decline would trigger a meaningful wave of forced selling, or whether Taiwanese regulators are moving toward system-wide limits rather than leaving risk management to individual brokerages.

For those building or investing in AI infrastructure, the concentration risk is worth watching closely. TSMC is too central to global semiconductor supply, and now too large a weight in global market cap rankings, for a leverage-driven reversal in Taiwan to stay neatly contained.