TAIEX Plunges 4.65% as AI Capex Doubts Trigger Taiwan’s Worst Chip Rout in Months

A 2,000-point intraday break

Taiwan’s stock market suffered its heaviest session in months on Tuesday, July 28. The TAIEX closed at 41,603.36, down 4.65%, after plunging more than 2,000 points intraday to a reported low near 41,565. The proximate trigger was a deepening loss of faith in the AI infrastructure spending cycle — sharpened by Alphabet’s recent report of negative free cash flow — which hit semiconductor supply chains across Asia. South Korea’s KOSPI reportedly fell more than 8% intraday, triggering circuit breakers, and Japan’s chip-heavy names sold off in tandem. The setup from New York was already soft: the Philadelphia Semiconductor Index dropped 2.23% at Monday’s US close even as the S&P 500 finished flat at +0.02%, and S&P futures drifted another 0.23% lower during Asian hours.

Local commentary flagged that the index has now lost both the 43,000 and 42,000 support levels in quick succession, leaving the quarterly moving average as the next technical reference for stabilization. During the session, more than half of the top 50 weighted stocks reportedly touched their daily limit down.

Semiconductors: the epicenter

TSMC, at nearly 3% down, was actually the market’s relative safe haven — its decline was the shallowest among the majors. MediaTek and UMC both closed effectively at the 10% limit, and memory names Nanya Technology and Winbond Electronics were reported locked limit-down at NT$392.00 and NT$144.00. The valuation backdrop helps explain the dispersion: as of Monday’s close, MediaTek traded at 58.65 times earnings and UMC at 31.66 times, versus Hon Hai at 17.97 times — the richest multiples took the hardest hits.

Institutional flows: foreigners sold NT$87.6 billion

The flow numbers, from official exchange data for July 28, tell an unambiguous story:

• Foreign investors: net SELL NT$87.56 billion
• Investment trusts: net buy NT$2.35 billion
• Dealers (proprietary + hedge): net sell NT$31.73 billion
• Three institutions combined: net sell NT$116.94 billion

Foreign money did the heavy lifting on the way down, dealers added to the pressure, and domestic investment trusts leaned very modestly against the tide. With foreign ownership at 69.27% of TSMC and 55.51% of MediaTek, foreign selling of this scale transmits directly into the index.

Positioning going in — Monday’s data, not today’s

Derivatives and leverage figures below are from the previous session (July 27); Tuesday’s data is not yet published, so read this as the posture markets carried into the crash rather than a reaction to it. Foreign investors held a net short of 78,699 contracts in TAIEX futures open interest as of Monday (net volume that day was a modest -1,246 contracts), and the options put/call ratio stood at 109.84% on open interest — a defensive but not extreme tilt.

Taiwan’s three leverage channels were each sending their own signal on Monday. Retail leveraged longs (margin purchases) were already shrinking: the market-wide margin loan balance fell NT$8.40 billion to NT$568.7 billion, with a notable unwind in UMC, where margin balance dropped 21,953 lots in one day. In the institutional short channel (securities lending), balances rose in 575 shortable issues against 312 declines — breadth tilted toward building shorts — with UMC’s SBL balance up 975,000 shares and TSMC’s up a marginal 59,000, while Hon Hai shorts were actually covered by 549,000 shares. In short: retail was deleveraging and institutions were selectively adding shorts before Tuesday’s break, which likely muted the forced-selling component of today’s decline.

Currency and the ADR gap

USD/TWD rose 0.22% to 32.39 — a weaker Taiwan dollar consistent with foreign equity outflows, but an orderly move relative to the equity damage. On the ADR side, TSM closed Monday in New York at $399.09, which now stands about 13.4% above the Taipei close. That gap is structural — the ADR has habitually traded at roughly a 15–25% premium in recent years due to limited fungibility — and the two closes come from different sessions, so the level itself signals nothing. What is worth noting is the change: Tuesday’s Taipei sell-off compressed the gap below its recent range, which mechanically points to pressure on the ADR in tonight’s US session unless sentiment turns.

What to watch

• Tonight’s US session: whether the Philadelphia Semiconductor Index extends Monday’s 2.23% drop, and whether the TSM ADR catches down toward Taipei or the premium re-widens toward its habitual band. Upcoming US mega-cap tech earnings are the swing factor for the AI capex narrative.
• Tuesday’s TAIFEX data, once published: whether foreign investors extended their 78,699-contract net futures short into the decline or used it to cover — the single best read on whether they treat this as a break or a flush.
• Follow-through in cash flows: a second consecutive day of NT$50 billion-plus foreign selling would confirm a positioning reset rather than a one-day shock, with the quarterly moving average the technical line the local street is watching.

Disclaimer: This is an information and analysis publication, not investment advice. See our Methodology for data sources, standards, and our corrections policy.