← Back to Blog · 2026-09-27 · 7 min read · Strategy Case Study

It's the spring of 2021. You're watching Chinese commodity futures go vertical. Rebar is ripping higher week after week, iron ore is printing record after record, and every trading group you're in is talking about "the China trade." You have no position. You watched the first leg of the move from the sidelines, waiting for a pullback that kept... not really pulling back. By the time you felt comfortable, you were chasing.

If that scenario stings a little, this article is for you. We're going to revisit the 2021 rebar bull run with cold eyes and ask a simple question: what would a boring, mechanical trend-following approach have actually caught — and, just as importantly, what would it have missed?

No hindsight heroics. No "we sold the exact top." Just a set of simple rules, applied to one of the most dramatic trends Chinese commodity futures have produced in recent years.

A Quick Recap of What Actually Happened

2021 was an extraordinary year for Chinese commodities, and you don't need to trust my numbers — the broad strokes are public record.

• The setup: Coming out of 2020, China's stimulus-driven recovery collided with deliberate supply-side constraints. Steel production caps, carbon emission targets, and output restrictions in major producing regions like Tangshan tightened supply just as construction demand roared back.
• The rally: Through late 2020 and into the first half of 2021, rebar futures on the Shanghai Futures Exchange climbed relentlessly, eventually pushing to levels well above anything the contract had seen before — roughly a doubling from the prior year's lows. Iron ore on the Dalian Commodity Exchange went even more parabolic, shattering its previous all-time highs.
• The intervention: In May 2021, senior Chinese policymakers publicly signaled concern about soaring commodity prices. The market took the hint. Rebar and iron ore both suffered sharp, violent corrections off the highs.
• The second act: After a choppy summer, the property sector — rebar's end market — began visibly deteriorating in the second half of the year (the Evergrande situation was impossible to miss). Rebar trended lower through autumn. Meanwhile, thermal coal staged its own legendary blow-off rally in September–October before regulators stepped in hard and the whole complex collapsed within weeks.

So the year gave us three distinct regimes: a strong uptrend, a violent reversal, and a strong downtrend. That's about as good a laboratory as a trend follower could ask for.

The Contract You'd Actually Be Trading

Before we talk strategy, let's ground this in the actual instrument. If you trade rebar, you're trading the RB contract on the Shanghai Futures Exchange (SHFE). Here are the specs that matter for sizing and risk:

A few practical notes. First, the 10-yuan tick value means a 100-yuan-per-ton move — which rebar could do in a single session during 2021's wildest days — is 1,000 yuan per lot. Size accordingly. Second, margin requirements on Chinese exchanges typically sit in the low double digits as a percentage, and exchanges raise them when volatility spikes (which they did, repeatedly, in 2021). Third, the night session matters: Chinese commodity futures often absorb global sentiment overnight, and gaps between sessions are a real feature of the market, not an edge case.

Iron ore (DCE, 100 tons per lot, 0.5-yuan tick size, so 50 yuan per tick) is the higher-octane sibling. If you trade iron ore, understand that its 2021 volatility made rebar look gentle.

The Rules of the Test

To keep this honest, I'm using a deliberately vanilla trend-following system — the kind you could code in an afternoon. Nothing optimized, nothing fitted to 2021 specifically.

Entry

• Go long when price closes above the highest high of the previous 20 sessions (a classic Donchian-style breakout).
• Go short when price closes below the lowest low of the previous 20 sessions.

Exit

• Exit longs on a close below the lowest low of the previous 10 sessions; exit shorts on a close above the highest high of the previous 10 sessions.
• Hard stop: 2 × the 20-day ATR from entry. Whichever exit triggers first wins.

Position sizing

• Risk a fixed 1% of the account per trade. Lots = (account × 1%) ÷ (stop distance in yuan per ton × 10 yuan contract multiplier).

That's it. A 20/10 Donchian channel with an ATR stop is roughly the skeleton of systems that have traded everything from crude oil to copper for decades. The question isn't whether the rules are clever. It's whether they'd have survived 2021's rebar market — a market that trended hard, reversed violently, and chopped mercilessly, sometimes in the same month.

What It Would Have Caught

The main uptrend, minus the first wiggle

Rebar's advance through late 2020 and into spring 2021 wasn't a smooth staircase — there were pullbacks sharp enough to knock out trailing stops — but the 20-day breakout structure would have re-entered after each shakeout. This is the underrated virtue of breakout entries: you don't need to be early, you need to be persistent. Each re-entry cost a little in whipsaws, but the trend paid for all of them many times over by the time price pushed into record territory around May.

On the way up, a 1%-risk-per-trade position would have pyramided naturally in the sense that later entries sat on open profit, and the 10-day trailing exit would have kept handing back only a modest slice of the move.

The downtrend in the second half

Here's where most discretionary traders got hurt: they were still mentally long. The property sector was cracking, production policy was shifting, and rebar rolled over through the autumn. A symmetrical system doesn't care about narratives — a 20-day breakdown is a 20-day breakdown. The short side of the second-half downtrend was, if anything, cleaner than the long side: lower highs, steady grind, no regulatory air pockets quite as violent as the coal complex experienced.

And note what the system would have been doing during the thermal coal madness: if it traded that market too, it would have caught a chunk of the September–October melt-up and then been flipped short by the breakdown after the government's intervention crushed prices in a matter of sessions. Trend following's ugly secret is that its best trades often come from exactly these "impossible" moves.

What It Would Have Missed (and Why That's Fine)

The exact top in May

When policymakers signaled concern about commodity prices, rebar didn't roll over politely — it dropped hard, fast, and with gaps. A 10-day trailing exit gives back the last stretch of any trend by design. If your system caught, say, the bulk of a move that roughly doubled, giving back the final high-single-digit or low-double-digit percentage is the fee, not a failure.

The summer chop

Mid-2021 was a whipsaw machine. Price oscillated, breakouts failed, and the system would have bled a series of small 1%-ish losses. This is the part of trend following nobody puts in the marketing material. Three, four, five consecutive small losses in a range-bound two months is normal, and if it feels unbearable, your position sizing is too aggressive — not your system.

The overnight gaps

Chinese commodity futures move while New York sleeps. When rebar gapped through a stop level after a policy headline, the fill would have been worse than the backtest assumed. Any honest assessment of trading Chinese commodity futures has to include this: your real-world results will be somewhat worse than your simulation, and the gap between them widens exactly when volatility explodes.

The point of a trend-following autopsy isn't to prove the system is a money printer. It's to confirm that the pain it inflicts — late entries, give-backs, chop losses — is survivable and priced in.

Practical Takeaways for Trading China's Commodity Markets

• Respect the multiplier. With a 10-ton contract and 10-yuan tick value, rebar lots add up faster than beginners expect. Compute your worst-case per-trade loss in yuan before you compute your expected profit.
• Policy is a market force. In China, a government statement about commodity prices is not noise — it's a regime change signal, as May 2021 and the thermal coal crackdown both proved. Trend systems survive this by having exits; discretionary traders survive it by having humility.
• Trade the trend, not the story. The second-half rebar downtrend was visible in price weeks before the fundamental narrative was fully confirmed. Price is the fastest fundamental data you'll ever get.
• Expect the chop, budget for it. If your risk-per-trade is 1%, a two-month losing streak is annoying, not fatal. If it's 5%, the same streak ends your account. The system didn't fail in the summer of 2021 — oversized accounts did.
• Backtest on real Chinese data. Chinese commodity futures behave differently from Western counterparts: different session structure, different participant mix, heavy retail influence, and a very active policy hand. A system validated only on US data tells you little about how it'll trade rebar or iron ore.

Test It Yourself, on Real Data

The 2021 rebar run is a great thought experiment, but thought experiments don't pay bills. What pays is knowing — before you risk real capital — how your rules handle a market that trends, reverses, and chops in the same year. That means running your approach against genuine Chinese futures data, with realistic tick values, session gaps, and margin dynamics, not a convenient approximation.

That's exactly what we built XS Select for. It's a China futures evaluation platform where you can put a systematic or discretionary approach through its paces on real Chinese commodity futures markets — rebar, iron ore, and beyond — with evaluations starting from $29. We're a new platform, so I won't tell you about our community of profitable traders; there isn't one yet. What I can tell you is that the 2021 rebar market is sitting there in the data, waiting to grade your system honestly.

The trend was there. The question is whether your rules would have been on it — and whether they'd have survived the parts that weren't.