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LE Paper 8 · Topic 5
This topic is where Paper 8 turns practical. Expect scenarios that hand you an order book, a session time or a trade and ask what OTP-C does with it, how CCASS settles it and what it costs. The calculation questions are trade-cost sums: brokerage, two levies, the trading fee and stamp duty, each with its own rounding rule. The rest tests the SFC's records, internal control, investor identification, conduct and electronic trading rules. Learn the session timetable, the order types, the fee table and the HKIDR consent rule cold.
14 min read8 sections
HKEX web pages and documents (checked 11 October 2026): Securities Trading Mechanism (OTP-C), Trading Hours, Severe Weather Arrangements, Pre-opening Session information book (10 April 2026), VCM Information Book (20 September 2024), Regulated Short Selling, Reduction of Minimum Spreads Phase 2 FAQ (8 May 2026), Derivatives Trading Mechanism, Clearing and Settlement Services, Guarantee Fund, Securities Transaction Fees and CCASS operational fees; Rules of the Exchange Chapter 5 and Second Schedule. SFO (Cap. 571) s.170; Cap. 571AJ rule 4; Cap. 571N s.6, s.55, Sch. 1; Cap. 571O s.3, s.10; Cap. 571Q s.5; Cap. 117 Sch. 1 head 2(1); Cap. 221 Sch. 8. SFC Code of Conduct (January 2026 edition), Management, Supervision and Internal Control Guidelines (April 2003), Guidelines for Reducing and Mitigating Hacking Risks Associated with Internet Trading (October 2017), HKIDR and OTCR web page. As at October 2026. Independent prep, not endorsed by HKSI Institute or the SFC.
SEHK's securities market trades on the Orion Trading Platform - Securities Market (OTP-C), an order-driven system. Rule 501 of the Rules of the Exchange and HKEX's trading mechanism pages set the sessions; the Pre-opening Session (POS) and Closing Auction Session (CAS) are auctions that match at a final indicative equilibrium price (IEP), while continuous trading matches in strict price and time priority. Since 23 September 2024 the market stays open in severe weather.
| Session (full day) | Time | What happens |
|---|---|---|
| POS order input | 9:00-9:15 a.m. | At-auction and at-auction limit orders entered, amended or cancelled; limit orders within 15% of previous close (Stage 1) |
| POS no-cancellation | 9:15-9:20 a.m. | New orders only, priced within the best bid and ask at 9:15 (Stage 2); no amendment or cancellation |
| POS random matching and blocking | 9:20 a.m. to up to 9:22, then to 9:30 | Orders match at the final IEP; nothing can be entered from matching until 9:30 |
| Continuous trading | 9:30 a.m.-12:00 noon and 1:00-4:00 p.m. | Limit, enhanced limit and special limit orders only |
| Closing Auction Session | 4:00 p.m. to a random close at 4:08-4:10 p.m. |
Every note. Every question. One pass.
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| Reference price = median of 5 nominal prices in the last minute; orders first within 5% of it; match at final IEP, or the reference price becomes the close |
| Order type | Where it may be priced | Unfilled balance |
|---|---|---|
| At-auction order (POS, CAS) | No price; matches first at the final IEP | Cancelled after the POS |
| At-auction limit order (POS, CAS) | Within the auction price limits | Carried into continuous trading as a limit order after the POS |
| Limit order | Sell not below best bid; buy not above best ask | Queued at its price |
| Enhanced limit order | Up to 9 spreads through the best price; sweeps up to 10 queues | Queued as a limit order |
| Special limit order | Any price through the best price, subject to the 9-times rule; sweeps up to 10 queues | Cancelled |
Prices move in steps set by the spread table (Second Schedule). For ordinary shares the minimum spread is HK$0.001 up to HK$0.25, HK$0.005 over HK$0.25 to HK$10 (Phase 2, from 3 August 2026), HK$0.01 over HK$10 to HK$20, HK$0.02 over HK$20 to HK$50, HK$0.05 over HK$50 to HK$100 and HK$0.10 over HK$100 to HK$200. Automatching trades in board lots, set per security; a quantity below one board lot is an odd lot, and one above a board lot but not a whole multiple is a special lot. A non-CAS stock's closing price is the median of five nominal-price snapshots taken every 15 seconds from 3:59 p.m.
Trap: applying the continuous-trading rules to the auctions. In the POS there are no limit orders, unfilled at-auction orders are cancelled, and the cancel window closes at 9:15 a.m., not at matching.
Takeaway: POS 9:00-9:30 with no cancelling after 9:15; continuous 9:30-12:00 and 1:00-4:00; CAS to a random 4:08-4:10 close.
The volatility control mechanism (VCM) covers Hang Seng Composite LargeCap, MidCap and SmallCap constituents, SPAC shares and warrants, and eligible ETFs and leveraged and inverse products. If an order would trade beyond the threshold from the last automatch price 5 minutes earlier, OTP-C rejects it and starts a 5-minute cooling-off period in which the stock trades only within that band. Multiple triggers per session are allowed. It applies to board-lot orders in continuous trading only, and is off for the first 15 minutes of the morning and afternoon sessions and the last 20 minutes of the afternoon session (HKEX VCM Information Book, 20 September 2024).
| VCM security | Trigger and cooling-off band |
|---|---|
| Hang Seng Composite LargeCap constituent | 10% either way |
| Hang Seng Composite MidCap constituent | 15% either way |
| Hang Seng Composite SmallCap constituent | 20% either way |
| Eligible ETFs and -1x inverse products | 5% either way |
Short selling on SEHK must be covered: the seller must have a presently exercisable and unconditional right to vest the securities in the buyer (SFO s.170; a breach carries a level 6 fine of HK$100,000 and 2 years' imprisonment). Short sales are allowed only in Designated Securities, revised quarterly, and the tick rule bars a price below the best current ask in continuous trading, below the previous close (the POS reference price) in the POS, and below the CAS reference price in the CAS. In the POS, short sales may be at-auction limit orders only. Large net short positions in specified shares (the lower of HK$30 million and 0.02% of the value of the issued shares) are reported weekly to the SFC within 2 business days after Friday (Cap. 571AJ).
Derivatives trade on HKATS, which matches orders in a central orderbook on price and time priority. Futures trades go to HKFE Clearing Corporation (HKCC) and stock options to SEHK Options Clearing House (SEOCH). Auction orders, used only in the pre-market opening period, match at the calculated opening price. Hang Seng Index futures trade 9:15 a.m.-12:00 noon and 1:00-4:30 p.m., plus an after-hours (T+1) session from 5:00 p.m. to 3:00 a.m.
Trap: treating the VCM as a trading halt. Trading continues inside the band for 5 minutes, then normal trading and monitoring resume.
Takeaway: VCM: 10/15/20% from 5 minutes ago, 5-minute band. Short sales: covered, Designated, never below the best ask.