March 2022: nickel prices went vertical — from ~$30,000 to over $100,000/tonne in days — and the London Metal Exchange, wholly owned by HKEX, used emergency powers to cancel US$12 billion of lawfully executed trades. It saved the clearing system from a default cascade. It also destroyed trust that took decades to build.
1. What actually happened
- A Chinese tycoon's giant short position (~180,000 tonnes) faced an unmeetable margin call as prices spiked
- If the member defaulted, the clearing house's default waterfall would have burned through member collateral — systemic failure
- The LME suspended trading, then voided the entire session's trades retroactively — including ones completed hours earlier
- Funds that had sold into the spike had their profits erased; the short seller's losses evaporated
2. The triple role conflict
| Role | What it wanted | Conflict |
|---|---|---|
| Market operator | Continuous, fair trading | Halted the market mid-crisis |
| Clearing guarantor | Prevent member default cascade | Chose system survival over trade sanctity |
| HKEX subsidiary | Protect parent's reputation + returns | Hong Kong shareholders inherit LME's operational risk |
RegSir's take
The LME was legally right — the rulebook's emergency powers existed, courts confirmed it — and institutionally catastrophic. The precedent it set: executed trades are provisional, not final. Markets price certainty; once participants learn that fills can be un-fills, liquidity reprices permanently. Nickel volumes never fully returned. For Hong Kong, the lesson is structural: HKEX's commodity expansion exported reputation risk home — the £13.8bn bet bought both diversification and a liability that materialised at the worst moment. An exchange's emergency powers should be exercised as surgery, not as a market-undo button.
3. Compliance takeaways
- Exchange counterparty risk is real: "the exchange guaranteed it" is not a complete answer — the exchange can also cancel it.
- Tail-event clauses in client agreements: if you offer access to markets with emergency powers, disclose that fills may be voided.
- Margin-model stress: exchanges' default waterfalls assume prices stay within bands — models need "gap beyond bands" scenarios, not just volatility scaling.
4. Official sources & reporting
| Document / report | Link |
|---|---|
| LME notices — nickel trading suspension & trade cancellation (March 2022) | lme.com ↗ |
| Elliott Management & Jane Street v LME — English High Court rulings | judiciary.uk ↗ |
| FCA enforcement — £9.2m fine on LME for systems & controls failures | fca.org.uk ↗ |