← Back to Blog · 2026-09-27 · 7 min read · Market Preview

You've done your homework. Steel inventories are drawing, mills are cutting output, and the macro tape says construction season is coming. So you go long rebar futures on the Shanghai Futures Exchange. Two weeks later, the physical steel market is firm, traders at the warehouses can't find cheap cargoes — and your futures position is flat or bleeding. What happened?

Chances are, the answer lives in the spread between the cash price and the futures price. In Western markets, traders call it basis. In China's commodity futures, basis isn't a nerdy detail for arbitrage desks — it's often the single most informative number on your screen. Ignore it, and you're trading a futures chart with one eye closed.

This article breaks down what basis is, why it behaves differently in China than in Chicago or London, the exact contract specs you need to know, and a few practical rules for folding basis into your trading — whether you trade rebar, iron ore, or the broader Chinese commodity futures complex.

What Basis Actually Is (and Why It's Not Just an Arbitrage Nerd's Toy)

Basis is simply:

Basis = Spot (cash) price − Futures price

In a perfectly efficient world, futures converge to spot at delivery. Between now and then, the futures price should roughly equal spot plus cost of carry (financing, storage, insurance) minus any convenience yield. When that relationship stretches, someone — usually well-capitalized players with warehouse access — steps in to arbitrage it back.

But here's the thing most retail traders miss: basis isn't just an arbitrage signal. It's a real-time sentiment gauge for the physical market. A rising basis (spot strengthening relative to futures) tells you physical buyers are paying up — demand is real, or supply is tight, right now. A collapsing basis tells you the cash market is softening even if the futures chart still looks bullish.

Futures can front-run, overshoot, and get carried by speculative flows. Cash is where actual steel, ore, and soybeans change hands. When the two disagree, the cash market usually tells you more about what happens next.

Why Basis in China Behaves Differently

If you learned basis logic from WTI or LME copper, you need to recalibrate for China. Three structural features change the game:

1. Retail-dominated flow, institutional-grade delivery

Chinese commodity futures markets have historically had heavy retail participation relative to CME or LME. That means futures prices can detach from cash far more dramatically — and stay detached longer — than Western textbook models suggest. Speculative momentum can push futures to levels no physical trader would pay. The correction, when it comes, tends to be violent.

2. Policy is a first-order variable

The clearest example is the thermal coal rally of 2021. Energy shortages, supply constraints, and speculative positioning drove coal futures to successive limit-up moves, with prices reaching multiples of where they'd traded for years. Then regulators intervened directly — the NDRC moved to cap prices, exchanges raised margins and restricted positions, and the market collapsed within weeks. Anyone reading only the futures chart missed both the blow-off and the cliff. The basis, and the growing gap between regulated physical pricing and unhinged futures pricing, was signaling the disconnect the entire time.

Iron ore told a similar story in 2021: a sharp rally to record territory followed by an equally sharp unwind as government pressure on steel output and commodity speculation kicked in. These aren't obscure events — they're the reason every experienced China futures trader keeps one eye on Beijing.

3. Delivery mechanics are strict and location-specific

Chinese exchanges enforce registered warehouse receipts, approved delivery brands, and designated delivery warehouses. The "spot price" you quote in your basis calculation has to match the deliverable grade and region, or your basis is fiction. Rebar delivered in Shanghai isn't the same trade as rebar in a regional market with a local discount. Getting the reference price wrong is the most common beginner mistake in Chinese commodity futures basis work.

Contract Specs You Actually Need (Quick Reference)

Before you trade basis on any Chinese commodity futures contract, know the delivery unit, because it defines the size of any cash-and-carry logic:

A few practical notes: iron ore at 100 tonnes per lot means a ¥10/tonne move in basis terms equals ¥1,000 per lot of futures exposure — it moves fast. Copper's small tick in percentage terms makes it the cleanest expression of the SHFE–LME arbitrage relationship, which is itself a cross-border basis trade. And note that thermal coal, after the 2021 intervention, has seen its liquidity and role change dramatically — don't assume historical behavior persists.

Also remember: margin requirements, position limits, and even trading hours (night sessions on SHFE and DCE) differ by contract and can change with little notice when exchanges decide to cool a hot market. Check current specs before every campaign, not once a year.

Reading Basis as a Directional Signal

Most retail traders treat basis as an arbitrage topic. But even if you never touch a delivery warehouse, basis gives you three actionable reads:

Signal 1: Basis trend confirms or contradicts your futures trend

If you're long rebar futures and the basis (spot minus futures) is widening — spot strengthening faster than futures — your trade has physical-market fuel behind it. If futures are rallying while basis collapses, you're likely riding speculative flow with no cash-market support. That's exactly the setup that preceded several of the sharp mean-reversions Chinese commodity markets are famous for.

A futures rally on collapsing basis is a rally you rent, not one you own.

Signal 2: Extreme negative basis (futures at a big premium to spot) is a warning

When futures trade at a large premium to cash — beyond what financing and storage costs justify — the market is pricing in a future that physical buyers aren't paying for yet. Sometimes that premium is justified (genuine expected shortage). Often it's speculative froth. Historically, when Chinese commodity futures have detached far above cash, the eventual convergence has been painful for late longs. You don't need to short it — but you should absolutely not buy it.

Signal 3: Basis seasonality in industrial metals

Rebar and construction-linked products follow China's construction calendar. Physical demand typically firms around the spring and autumn construction windows and softens through winter, when northern sites slow down and winter production restrictions historically kick in. Basis tends to reflect this rhythm before the futures crowd fully prices it. Combine basis seasonality with your futures setup and you have a genuine edge in timing entries — not a crystal ball, but a filter.

Practical Rules for Trading Basis in Chinese Commodity Futures

Here's how to operationalize this without overcomplicating your process:

• Pick the right spot reference. Use a published regional spot price for the deliverable grade — for rebar, a major benchmark quotation for HRB400 rebar in a delivery-region market; for iron ore, a quoted price for the fines grade that matches DCE deliverability. Mismatched grades produce garbage basis.
• Track basis daily, not just price. A simple spreadsheet: date, spot, front-month futures, basis, basis change. Ten seconds a day. The trend of basis over two to four weeks tells you more than any single reading.
• Use basis as a veto, not a trigger. Don't go long just because basis is strong. Do refuse longs when basis is collapsing against you. It's a filter that keeps you out of the worst trades, which in a leverage-heavy market is worth more than finding the best ones.
• Respect the calendar rolls. Chinese industrial contracts have active months that cluster around delivery cycles. Basis versus the front month behaves differently near delivery than in the back — compare spot to the contract you actually trade, and be aware that rolling costs show up in the spread, not in your P&L line item.
• Watch policy headlines as basis events. When NDRC commentary, output restrictions, or exchange margin hikes hit the tape, basis relationships can gap. In China, a regulatory headline is a market event the way an FOMC statement is in the US.
• Size for the disconnect, not the trend. Because Chinese commodity futures can gap on limit moves and policy shocks, position sizes that feel comfortable in trending Western markets can be too aggressive here. Assume your stop won't always fill where you want it.

Where Basis Meets Your Evaluation Journey

None of this requires you to become a physical trader or rent a warehouse in Tangshan. It requires one habit: before every trade in Chinese commodity futures, ask what is the cash market doing relative to my contract, and is that relationship confirming or contradicting my thesis? That single question would have kept traders out of the worst moments of the 2021 coal and iron ore episodes — and kept them in genuinely demand-backed moves.

Like any edge, it's only real if you can execute it under pressure, with real market data and real risk rules. That's exactly what a structured futures evaluation is for: testing whether your basis-filtered system survives a defined drawdown limit and profit target, not just a backtest. If you want to put a China futures strategy through that kind of test on live market data, XS Select runs real-data evaluations for Chinese commodity futures starting from $29 — a low-friction way to find out whether your process holds up before your own capital does.

Basis won't make your trades for you. But in a market where policy, speculation, and physical reality collide as violently as they do in China, it's the closest thing you have to hearing what the actual market — not just the futures tape — is saying. Listen to it.