Taiwan Stock Market Rule-Change Timeline: Price Limits, Matching, Odd-Lot, Tick Size and Settlement

Daily price limit: ±7% → ±10% (1 June 2015)

The daily price limit on listed common stocks was ±7% of the previous close for years, through the last trading day of 29 May 2015, and was widened to ±10% from 1 June 2015 — the level still in force. This is the single most important break for daily-return work, because it changes the maximum possible one-day move. Confidence: high (the 2015 widening is officially documented and widely reported).

Intraday matching: call auction → continuous matching (23 March 2020)

Until 22 March 2020 intraday trades were matched by call auction (a match roughly every few seconds); continuous matching took effect from 23 March 2020. This changes intraday microstructure — fills, spreads, tick-by-tick behaviour — not the daily percentage move, so it matters for intraday models rather than end-of-day factors. Confidence: medium (we are still confirming the exact final call-auction session against the official announcement).

Intraday odd-lot trading (26 October 2020)

Odd lots (1–999 shares) could only be traded in a separate after-hours session until 23 October 2020; regular-session intraday odd-lot trading launched on 26 October 2020. If you study small-order or retail-sized activity, odd-lot volume before that date is not comparable to after it. Confidence: high. Source: Taiwan Stock Exchange — twse.com.tw/market_insights/zh/detail/8a8216d6933460a401936c53f6d9018e

Tick size: current 6-tier table (1 March 2005)

The minimum price increment steps up by price band, and the tier table in force today took effect on 1 March 2005. The coarser pre-2005 tiers are not listed here — there is no verified official source for them on hand, and we will not guess. Confidence: high for the 2005 table. Source: Taiwan Stock Exchange — twse.com.tw/downloads/zh/trading/introduce/introduce004.pdf

Same-day (day) trading: opened in stages, dates being verified

Same-day 'buy-first' day trading opened first and 'sell-first' was broadened a few months later, both around 2014; the day-trade securities-transaction-tax was later halved (to 0.15%), around 2017. These mark a rise in turnover and short-horizon activity that shifts volume and volatility baselines. Confidence: needs verification — treat 'around 2014' and 'around 2017' as approximate; we do not state a precise date we have not confirmed.

Settlement and ex-rights reference (stable)

• Settlement cycle — T+2 (high confidence): Taiwan equities settle two business days after the trade. Stable; affects when cash and delivery land, not the price series.
• Ex-rights / ex-dividend reference price (high confidence): computed from the official TWSE TWT49U calculation, the same source behind the ex-rights price-adjustment factors — no separate regime date is needed.

How to use this timeline

Rather than hardcode any of these, split a long sample at the dated breaks, or tag each row with the rule that actually applied. For the daily price limit specifically, the stock-price-limit-daily dataset gives the per-day limit-up / limit-down price so limit-hit days are handled automatically across 2015. The entries marked 'needs verification' are research stubs — we raise them to dated facts only once checked against an official source, never by guessing.

常見問題