← Back to Blog · 2026-09-27 · 8 min read · Strategy Case Study

Picture this: you've been long thermal coal futures for two months. Every pullback gets bought. Every new high confirms you were right. Your equity curve looks like the chart itself — vertical. Then one Tuesday evening, a government agency issues a statement about coal prices, and over the next week the market locks limit-down day after day. You can't get out. Nobody can.

That's not a hypothetical. That's roughly what happened to traders holding Chinese thermal coal futures in October 2021. It's one of the best natural experiments you'll ever see for stress-testing a momentum strategy — because the same market that rewarded momentum ruthlessly well also punished it ruthlessly fast.

Let's walk through it like traders, not historians: what happened, how a disciplined momentum system would have navigated it, and what the whole episode teaches anyone trading Chinese commodity futures today.

What Actually Happened in 2021

Quick recap for anyone who wasn't watching China markets that year. Through 2021, China's economy was rebounding hard while coal supply was constrained — mine safety inspections, import restrictions, and surging post-pandemic electricity demand all squeezed the balance. Power rationing hit factories in the second half of the year. Thermal coal futures on the Zhengzhou Commodity Exchange became the pressure valve.

The rally was extraordinary. Thermal coal roughly tripled from mid-year levels and peaked around the 1,900 yuan/ton area in mid-October — a parabolic move on a contract that had traded in a fairly boring range for years. Volume and open interest exploded alongside it.

Then the policy response. In mid-October, the NDRC signaled it would intervene directly in coal pricing — studying ways to cap prices and releasing reserves. The exchanges piled on: repeated margin hikes, tighter position limits, expanded price bands in some sessions. The result was a brutal unwinding: thermal coal futures posted multiple consecutive limit-down days and gave back roughly half the entire rally within a matter of weeks.

Two things made this episode uniquely dangerous compared to, say, the 2020 oil crash:

• It was policy-driven, not fundamentals-driven. The supply-demand picture didn't change overnight. The rules of the game did.
• Liquidity vanished on your side of the trade. During consecutive limit-downs in a long position, there are simply no sellers willing to take the other side at the limit price. Your stop-loss becomes a suggestion, not an order.

Keep those two facts in mind. They're the entire reason this case study matters.

The Strategy: A Simple Momentum System, Fully Specified

For this exercise, let's use a deliberately plain trend-following system — the kind you could code in an afternoon. No machine learning, no order-flow secrets. Just rules.

Instrument and Contract Specs

Thermal coal futures (ticker ZC), Zhengzhou Commodity Exchange:

One lot moves 20 yuan per tick, so at 1,500 yuan/ton, a single 1% daily move equals roughly 1,500 yuan per lot. Do that math before every trade in Chinese commodity futures — the multipliers mean small-looking price moves are not small-looking P&L.

Entry Rules

• Enter long on a close above the highest high of the prior 20 sessions (a classic Donchian-style breakout).
• Only take the trade if the 50-day moving average is above the 200-day — trade with the macro trend, not against it.
• Pyramid: add one unit for every additional 1×ATR(20) move in your favor, up to a maximum of 3 units.

Exit and Risk Rules

• Initial stop: 2×ATR(20) below entry.
• Trailing stop: 3×ATR(20) below the highest close since entry — this is the exit that lets you ride a parabola.
• Risk per unit: 1% of account equity, calculated as (stop distance × contract multiplier × lots). Never fudge this.
• Hard rule: if the exchange announces a margin hike or position limit change, halve new position sizing immediately. Policy attention is a risk signal, not noise.
• Hard rule: no new entries after a vertical move of more than roughly 50% in 20 sessions. Parabolic markets are where trend-following profits go to die.

That last rule is the one most retail traders skip. Remember it for later.

On the Way Up: Where Momentum Earned Its Keep

Run the tape mentally. Through the summer of 2021, thermal coal kept printing higher highs. A 20-day breakout system would have been stopped out once or twice early on — that's normal, trend systems lose on most individual trades — and then caught the major leg sometime in the late-summer acceleration.

This is where the system's design pays off:

• The ATR-based trailing stop never caps the upside. As volatility expanded — and ATR expanded massively — the stop ratcheted up behind the move, giving the position room to breathe while locking in gains.
• Pyramiding into strength meant the biggest position sizes sat on the newest, most fragile part of the trend. That's the trade-off you accept for trend-following: your average entry is late, but your exposure is largest exactly when the trend is most confirmed.
• The 1% risk rule kept the position small enough that even a violent single-day reversal was survivable.

By mid-October, a disciplined trader riding this move was sitting on a serious open profit — likely one of the best trades of their year, on any market. And that's precisely when the system's real test arrived. Not the entry. Not the ride. The exit.

The Reversal: Where Momentum Strategies Go to Die

Here's the uncomfortable sequence. The NDRC statement lands mid-October. The market gaps down hard. Then it locks limit-down. Then again. For a long trader, a locked limit-down means the order sits in the queue and may simply not fill. Your trailing stop — 3×ATR below the high — is now a theoretical level several percent below a price at which no trade is occurring.

Let's be honest about what the backtest says versus what reality does:

• Backtest version: the trailing stop triggers, you exit near the stop level, you give back maybe 10–15% from the peak. Annoying but fine.
• Real version: you give back far more, because fills happen at whatever price the queue finally clears at — potentially one or two limit-down sessions lower. Slippage on policy-driven reversals in Chinese commodity futures isn't measured in ticks; it's measured in whole limit moves.

This is the core lesson of the entire case study: momentum strategies don't fail because they can't detect reversals. They fail because the exit they designed doesn't exist when they need it. A stop-loss is only as good as the liquidity behind it, and liquidity is exactly what disappears when the catalyst is a government statement rather than a change in supply-demand.

Would our system have survived? Yes — but only because of the rules most traders consider optional:

• The parabolic-move filter (no new entries after a ~50% move in 20 sessions) would have kept anyone from adding fresh risk in the final weeks, when late longs were most crowded.
• The policy-response rule (halve size when margins get hiked) would have cut exposure before the worst sessions, because the exchange's margin hikes were a visible, public warning shot.
• The 1% risk sizing meant that even with catastrophic slippage — say, exiting two limit-downs below the stop — the damage was a dent, not a knockout.

The trend rider who ignored all three? Depending on leverage, a string of locked limit-downs at 8% daily moves against a heavily margined position isn't a drawdown. It's an account-ending event. Chinese exchanges can and do raise margins mid-trend specifically to force deleveraging, which can trigger the very liquidation cascades traders fear.

What This Means for Rebar, Iron Ore, and Other Chinese Commodity Futures

If you trade rebar, iron ore, or other Chinese commodity futures, you might be tempted to file this under "coal thing, not my problem." Don't. The 2021 thermal coal episode is a template, and the pattern has cousins across China's markets: policy is a first-class market participant. Steel output restrictions, property-sector measures affecting construction demand, environmental production cuts — these all land on rebar and iron ore with the same abruptness that the NDRC statement landed on coal.

So here's the practical adaptation, regardless of which Chinese contract you trade:

• Track policy flow like it's a technical indicator. Regulatory statements, exchange margin notices, and position limit changes are leading signals of intervention risk. Build a habit: check exchange notices before every session.
• De-risk into strength, not just into weakness. Trend-following purists hate taking partial profits, but in policy-sensitive markets, banking a portion of a parabolic move is buying insurance against a gap you cannot trade through.
• Size for the exit you'll actually get, not the exit you want. Assume your worst-case fill is one to two limit moves beyond your stop. If that scenario would hurt more than 3–5% of your account, your position is too big.
• Respect contract multipliers. Whether it's thermal coal at 100 tons/lot or rebar at 10 tons/lot, convert every stop distance into actual yuan before you click buy. Most retail blowups in China futures are sizing errors, not directional errors.

The Meta-Lesson: Backtests Lie About Liquidity

If there's one takeaway to tattoo somewhere visible, it's this: standard backtesting silently assumes you can always exit at your stop price. The 2021 thermal coal reversal is the counterexample that breaks that assumption. Any honest evaluation of a momentum strategy on Chinese commodity futures has to model limit-locked sessions, policy-driven margin changes, and slippage that scales with volatility — not with your optimism.

That's also why testing against real Chinese market data, including genuinely ugly periods like late 2021, matters so much more than testing on a clean synthetic series or a friendly stretch of the trend. A system that only looks good on smooth data is a system that hasn't met its October yet.

Putting It to Work

So, would a momentum strategy have handled the 2021 thermal coal squeeze? The honest answer: it would have made a fortune on the way up, given a meaningful chunk back on the way down, and survived — if and only if the position sizing and policy-awareness rules were non-negotiable. The trend was tradeable. The exit was the trap. The difference between the traders who came out fine and those who didn't wasn't the entry signal. It was everything around it.

If you're running a momentum or breakout system on Chinese commodity futures — or thinking about it — don't take my word for how it would behave under a policy shock. Test it. At XS Select, you can run your system through a structured futures evaluation on real China market data starting from $29, and see exactly how your rules hold up when the tape stops cooperating. No promises about outcomes — just a cleaner answer than guessing.

The market will always hand you a thermal coal eventually. The question is whether your rules will be ready for the Tuesday evening statement.