Taiwan’s stock market suffered its roughest session in months on Thursday, October 15. The TAIEX fell 1,655.96 points, or 3.41%, to close at 46,969.87 — back below the 47,000 mark and its monthly moving average — on heavy turnover of NT$1.32 trillion. The trigger came from overnight New York: US September CPI printed at 3.7% year-over-year against a 3.6% forecast, reviving hawkish Fed expectations and hitting AI-infrastructure trades hard. The Philadelphia Semiconductor Index lost 4.30% in Wednesday’s US session and the S&P 500 fell 1.11%, and Taipei absorbed the full force of that move at the open and never recovered.
Flows: a record-breaking foreign exit
The flow data is the story of the day. Foreign institutional investors net sold NT$302.56 billion in the cash market — a record single-day figure. Proprietary dealers added NT$95.82 billion of net selling. Domestic investment trusts leaned the other way, net buying NT$28.30 billion, but that was a bucket against a tide: the three institutional categories combined were net sellers of NT$370.08 billion.
The currency told the same story. USD/TWD was quoted around 32.39 on Thursday, roughly 0.9% higher, as equity outflows were converted, leaving the Taiwan dollar at its softest level since early August by local accounts.
The tape: semis led the damage
| Name | Close (NT$) | Change |
|---|---|---|
| TAIEX | 46,969.87 | -3.41% |
| TSMC (2330) | 2,440.00 | -2.01% |
| MediaTek (2454) | 4,165.00 | -6.93% |
| UMC (2303) | 133.50 | -5.99% |
| Hon Hai (2317) | 239.50 | -1.44% |
The electronics sub-index fell 3.63%, with the weakness echoed across the region in Tokyo and Seoul. Notably, the high-multiple names took the worst of it: MediaTek went into the session at roughly 74x trailing earnings and nearly 17x book (per Wednesday’s TWSE figures), and Delta Electronics — at 57x earnings — was among the day’s steepest heavyweight decliners alongside DRAM maker Nanya Technology. TSMC and Hon Hai, at 28.9x and 16.0x respectively, fell far less. On a day driven by rate fears, the market repriced duration, not fundamentals.
TSMC: record numbers into a falling tape
The irony of the session: TSMC delivered a blowout third quarter at its afternoon investor conference. Net revenue hit a record NT$1,494.24 billion (US$46.72 billion), up 50.9% year-over-year, with net income of NT$763.06 billion (up roughly 68.8%), EPS of NT$29.43 and a 66.4% gross margin. CEO C.C. Wei reaffirmed that AI hardware demand remains “extremely robust.” The stock still closed down 2.01% — the results landed after the 13:30 close, so Friday’s open is the first clean read on how the market weighs record earnings against the macro backdrop.
One cross-market note: the TSM ADR closed Wednesday’s US session at $430.00, which puts the ADR premium over the Taipei close at about 14.1% — toward the low end of the roughly 15–25% structural range it has carried in recent years. Remember this gap is structural (limited fungibility) and compares closes from different sessions; the level is not a mispricing signal. It is day-to-day changes in this gap, not its level, that carry the signal — and tonight’s US session, the first since TSMC’s results, provides the next reading.
Positioning going into the drop
A caveat up front: derivatives and leverage data below are from Wednesday’s session (October 14) — Thursday’s figures aren’t published yet — so they describe the setup going into today’s fall, not the reaction to it.
- Futures: Foreign investors carried a net short of 86,814 TAIEX futures contracts into the session (Wednesday’s net volume was a marginal +738), so the record cash selling landed on top of an already-defensive derivatives book.
- Options: The volume-based put/call ratio stood at 103.47% on Wednesday — mildly put-tilted, not extreme.
- Retail leverage (margin purchases): The market-wide margin loan balance rose NT$6.59 billion to NT$651.6 billion on Wednesday — retail was adding leveraged longs ahead of the drop, including +897 lots in TSMC and +5,129 lots in UMC.
- Institutional shorts (SBL): Securities-lending short balances rose in 575 issues versus falls in 256 on Wednesday — broad-based institutional short-building, with UMC (+571,000 shares) and MediaTek (+60,000) among the adds, while Hon Hai shorts were trimmed slightly.
Taken together, the setup showed institutions hedged and shorting into the event while retail leverage crept higher — a combination that tends to amplify a gap lower. Thursday’s TAIFEX and margin data, out tomorrow, will show whether foreign futures shorts were extended or covered into the fall.
What to watch
- Friday’s reaction to TSMC’s results — record revenue and a 66.4% gross margin landed after the close; the TSM ADR’s US session tonight is the first verdict, and watch the day-to-day change in the ADR–Taipei gap rather than its level.
- Whether the foreign selling has a second day — NT$302.56 billion is a record; follow-through would keep pressure on USD/TWD above 32.
- TAIFEX final settlement on Wednesday, October 21 — with foreign futures positioning already net short 86,814 contracts as of October 14, expiry week mechanics could add volatility in either direction.
Disclaimer: This is an information and analysis publication, not investment advice. See our Methodology for data sources, standards, and our corrections policy.