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What happened 

Shares of aluminum producer Century Aluminum Co (CENX -0.72%) jumped as much as 15.6% on Thursday after the U.S. launched a trade complaint that could help the domestic aluminum industry overall. At 11:50 a.m. EST, shares were still up 12.8% on the day. 

So what

The U.S. officially filed a trade complaint with the World Trade Organization that accuses China of expanding its aluminum production through cheap loans provided by state-run banks and subsidized energy prices. Subsidies have allowed Chinese aluminum producers to flood the market with cheap, subsidized aluminum and take market share from other countries around the world, according to the complaint. 

If it's successful, this complaint could lead to tariffs that would make Chinese aluminum more expensive here in the U.S., helping manufacturers like Century Aluminum. 

Now what

It's uncertain if or how this trade complaint will impact Century Aluminum's bottom line, but any help the company can get will be welcome. Over the last year, the company has lost $127.0 million, and there's no indication losses will stop without a large increase in aluminum prices. The speculation for today is that some help could be coming from the government. That's a risky justification to buy the stock, but that's what has it moving higher today.