After falling by 5% in Tuesday's daytime session, tin hit a three-year low overnight before clawing back some ground but still ended down almost another 4%. It has lost 8.6% this week and around 9.9% so far in 2019.
"The overall pattern of weak supply and demand remains unchanged," Citic Futures said in a note, adding that there was no obvious reason for the deterioration and that the price movements were fund-driven. Chinese tin smelters are all losing money at these price levels, it added.
The China branch of the International Tin Association said in a note that tin supply was still tight.
China's refined tin production in the first five months of 2019 had fallen around 10% year-on-year, while ore imports from neighbouring Myanmar were down 33% on a tin content basis, it said.
FUNDAMENTALS
* TIN: The most traded September tin contract on the Shanghai Futures Exchange fell as much as 7.2% overnight to 127,780 yuan ($18,559.73) a tonne, its lowest since June 30, 2016, but rallied to close down 3.8% at 132,500 yuan.
Three-month tin on the London Metal Exchange was up 0.5% at $17,785 a tonne as of 0737 GMT, after shedding 6.4% on Tuesday, when it touched its lowest since August 2016.
* SHFE: Market open interest in Shanghai tin surged to the highest since November at 52,042 lots on Tuesday, as short positions increased, while the trading volume in Shanghai tin had was around 162,500 lots on Wednesday, 11 times greater than the full-day average for the past 30 days.
* COPPER: Three-month LME copper slipped 0.2% to $5,873 a tonne as the dollar strengthened, while ShFE copper closed down 1% on 46,250 yuan.
* ALUMINIUM: Aluminium producer Alcoa Corp said it expects to incur a charge of between $40 million and $50 million in the second half of 2019, related to restarting operations at its Canadian smelter in Becancour, Quebec.
* EXCHANGE: Qianhai Mercantile Exchange, a mainland China physical commodities bourse owned by Hong Kong Exchanges and Clearing Ltd, has started spot trading of aluminium ingots and billets.