In May, the global aluminum market continued the core pattern of LME outperforming SHFE with divergent trends. The most-traded SHFE aluminum contract moved sideways in the doldrums, while LME aluminum maintained strength supported by low inventory and geopolitical premiums, with both seeing slight corrections at month-end.
This month's market-driving logic revolved around Middle East ceasefire negotiations, rising expectations for US Fed interest rate hikes, divergence in inventory in and outside China, and accelerating export transmission, further highlighting the divergence between domestic and overseas aluminum price trends. The SHFE/LME aluminum price ratio declined further from the April average of 7.03 to the May average of 6.66, with the inverted price spread between domestic and overseas markets widening, as the trend of overseas aluminum prices outperforming SHFE aluminum continued to deepen.
May Aluminum Price Review: Similar Pace but Intensifying Divergence in Strength
China · The Most-Traded SHFE Aluminum Contract
The contract opened low at around 24,800 yuan/mt at the beginning of the month. After the holiday, it pulled back rapidly due to high domestic inventory and weaker-than-expected downstream demand, hitting the monthly low of 24,075 yuan/mt on May 7. In mid-month, it rebounded to 24,620 yuan/mt driven by positive signals from the China-US meeting. In the latter part of the month, it pulled back to 24,375 yuan/mt as ceasefire expectations heated up combined with off-season drag.
Ex-China · LME Aluminum
The contract opened at $3,480/mt at the beginning of the month. In mid-month, it rallied to $3,680/mt (the monthly high and a four-year high) supported by supply disruptions and continued destocking. At month-end, it corrected to $3,628/mt, impacted by news that a US-Iran ceasefire agreement was 95% reached.
In terms of price-driving factors, geopolitics remained the core common variable for aluminum prices in and outside China this month. Production cuts in the Middle East and shipping disruptions through the Strait of Hormuz continued to provide a shortage premium for LME aluminum. The price divergence stemmed from dual differences in macro policy and fundamentals—slow destocking from high inventory levels in China constrained SHFE aluminum's rebound space, while historically low inventory and a high premium structure outside China provided strong support for LME aluminum prices.
Core Inventory Indicators: Extreme Divergence Between Domestic and Overseas Inventory with Contrasting Destocking Pace
China · Gradual Decline from High Levels, Pressure Persists
Social inventory began to pull back from the high of 1.456 million mt at the beginning of May, reaching approximately 1.401 million mt by month-end, with only about 55,000 mt destocked over the entire month. The destocking pace was slow, with inventory remaining at a near six-year high for the same period. SHFE warrants recorded 485,500 mt on May 29, still showing inventory buildup on a weekly basis, confirming ample spot supply in China.
Ex-China · 20-Year Low, Structural Deficit Becomes Evident
LME total inventory declined from approximately 363,000 mt at the beginning of the month to 338,000 mt at month-end, a decrease of approximately 25,000 mt over the month, with inventory levels at historically extreme lows. LME aluminum Cash-3M premiums closed at $92.53/mt at month-end, widening significantly from approximately $29/mt at the beginning of the month. Japan's Q3 spot premiums rose, premiums in Europe and the US continued to climb, and the rigid supply gap outside China provided sustained and strong support for LME aluminum.
Macro and Fundamentals Intertwined: Geopolitical Dynamics and Rate Hike Expectations Dominating Sentiment
Geopolitical Variables: Repeated Ceasefire Negotiations
At the beginning of the month, the US military launched airstrikes on southern Iran, with military frictions between the two sides recurring. Shipping through the Strait of Hormuz remained disrupted, and geopolitical risk premiums climbed. At month-end, a US-Iran framework agreement was reportedly 95% complete, and a 60-day temporary ceasefire draft emerged. Expectations for the resumption of strait navigation warmed, and geopolitical premiums converged significantly. On the morning of May 28, both SHFE aluminum and LME aluminum plunged.
US Fed Expectations: Hawkish Pressure
US April CPI came in at 3.4% YoY, with core PCE reaching 2.8%. Inflation stickiness, compounded by Middle East conflicts pushing oil prices above $90/barrel, led hawkish US Fed officials to release signals of "raising rates at any time." Market expectations for a 25bp rate hike within the year surged abruptly, and a stronger US dollar continued to weigh on the demand outlook for non-ferrous metals.
IV. Current Core Market Trades and Arbitrage Strategies (Including Divergence in Capital Behavior)
Based on the current SHFE and LME fundamentals, inventory pace, and LME curve structure, the aluminum market overall exhibits a cautious unidirectional and arbitrage-dominated trading pattern. In particular, SHFE-LME cross-market reverse arbitrage (selling SHFE and buying LME) has become the core market play. Capital behavior among market participants has shown clear divergence, mainly falling into three categories:
1. Early-positioning capital (light long positions in reverse arbitrage)
Some trading capital has positioned reverse arbitrage ahead of time based on the logic that China's inventory inflection point has already appeared. The core expectation of such capital is that as China's inventory gradually enters a destocking channel, accelerated destocking is highly likely to follow, rapidly easing China's high inventory pressure. The weak SHFE aluminum pattern is expected to be corrected, and the depressed SHFE-LME ratio has clear room for recovery, warranting early light positioning to capture the ratio rebound.
2. Wait-and-see cautious capital (staying on the sidelines for now)
The majority of market capital has maintained a wait-and-see stance, with two core concerns: First, China is currently only experiencing slow destocking, and its sustainability is questionable during the off-season, as inventory pressure has not been substantially cleared and SHFE aluminum lacks sufficient rebound momentum. Second, LME is currently in a deep backwardation structure, making roll and extension costs for LME aluminum bulls extremely high, with significant cost erosion and high open interest pressure for holding long-term reverse arbitrage positions. Combined with the entrenched short-term pattern of LME outperforming SHFE, the price spread still risks further widening. Therefore, this segment of capital has chosen to wait for confirmed signals of accelerated destocking in China before entering the market.
3. Previously trapped capital (open interest under pressure, caught in a dilemma)
Some positions that were established earlier to set up SHFE-LME reverse arbitrage are currently slightly underwater. Recently, LME has been continuously driven higher by geopolitical risks while SHFE has been range-bound and weak, with the divergence between LME outperforms SHFE intensifying, causing the ratio to remain persistently low and unrealized losses to emerge. Meanwhile, LME contango fees have risen sharply, long positions carrying costs continue to increase, and the pressure of holding trapped positions has further intensified. In the short term, these positions are caught in a dilemma, highly dependent on the subsequent pace of China's inventory destocking to restore the spread.
Overall, the sole core inflection variable for SHFE-LME reverse arbitrage is currently the pace of domestic inventory destocking. Once weekly inventory drawdowns continue to widen and accelerated destocking is confirmed, it will directly drive a reversal in three types of capital behavior: sidelined capital entering the market en masse, trapped positions getting unwound, and early-entry positions realizing profits, triggering a rapid recovery in the ratio.
Looking ahead to June,
the aluminum market's core focus centers on three dimensions: first, whether the US-Iran ceasefire agreement can be formally signed and the pace of resuming navigation through the Strait of Hormuz, which will directly determine the extent of geopolitical premium convergence — if the agreement materializes and Middle Eastern aluminum supply gradually recovers, the prior support logic for LME aluminum faces correction risk; second, whether domestic inventory destocking can accelerate — continued export growth and import suppression will keep driving destocking, and the magnitude of destocking will determine SHFE aluminum's upside elasticity.
The US Fed's June FOMC meeting is highly likely to keep rates unchanged, but a hawkish tone and sticky inflation will continue to suppress interest rate cut expectations, with a stronger US dollar maintaining sustained pressure on non-ferrous metals. Overall, the aluminum market in June is expected to continue the pattern where LME outperforms SHFE, though the degree of divergence is likely to narrow. LME aluminum is expected to hover at highs amid the tug-of-war between geopolitical premium convergence and rigid ex-China supply deficits, with downside room constrained by low inventory and high premiums.
[ Data source disclaimer: Data other than publicly available information is derived from public information, market communication, and SMM's internal database models, processed by SMM for reference only and does not constitute decision-making advice. ]
Data source: SMM
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