Taiwan’s benchmark surged 663 points to 45,832.62 on Wednesday as silicon photonics and CPO names hit limit-up, MediaTek jumped 5.6%, and all three institutional camps bought — foreign investors alone adding NT$36.6 billion.
Taipei shrugged off a weak Wall Street session on Friday: the TAIEX rose 0.65% to 45,224.29 on heavy foreign buying, with TSMC up 1.47% and MediaTek up 2.43%. We break down the flows, the previous-session futures positioning, and the short channels.
Taiwan’s benchmark swung more than 700 points intraday before closing up 0.48% at 44,933.74, as TSMC’s late push to NT$2,375 offset an overnight 2.12% drop in the Philadelphia Semiconductor Index. Foreign investors bought NT$3.78B while dealers sold, and capital rotated hard into shipping.
TAIFEX Taiwan index futures stop trading on the third Wednesday of each month, and the final settlement price is an arithmetic average of TAIEX values over the last 30 minutes of the spot session (13:00-13:30 Taipei) — not the closing print. Here is how the calendar, the averaging window, and expiry-week rollover actually work, with a worked example reading foreign net open interest.
Taiwan stocks fell 1.30% on Wednesday, breaking below 45,000, after a near-5% overnight plunge in the Philadelphia Semiconductor Index. All three institutional groups sold, totaling NT$70.85 billion, on TAIFEX settlement day.
Taiwan’s benchmark reversed an early gain to close at 45,308.68 on Tuesday, with MediaTek down 4% and all three major institutional groups except investment trusts selling. Futures settlement looms Wednesday.
The TAIEX rose 1.11% to 46,021.48 on Thursday, a fourth straight gain, as a cool US CPI print and a 2.49% SOX rally powered semiconductors. Foreign investors net bought NT$75.69 billion in the cash market, MediaTek jumped 5.23%, and Hon Hai bucked the tape.
TAIFEX publishes foreign investors’ net open interest in TAIEX futures and the options put/call OI ratio every trading day — but a large negative net OI is usually a hedge, not a bearish bet. Here is how to read both gauges, with a worked example from real August 2026 data, the practitioner heuristics and their limits, and the divergences that matter.
The TAIEX closed at 45,518.07 on Wednesday, up 0.88%, as TSMC’s record NT$467.58 billion July revenue and a fresh capex approval lifted the tech complex. All three institutional groups were net buyers, led by NT$11.02 billion of foreign inflows, with the US CPI print looming overnight.
Taipei reversed an early 276-point drop to close up 0.43% at 45,120.72 on Tuesday, defying a 2.94% overnight slide in the Philadelphia Semiconductor Index. Foreign investors net bought NT$22.33 billion, MediaTek and TSMC led the recovery, and passive-component names went limit-up on AI server demand.