PITTSBURGH—The world's biggest aluminum maker by revenue wishes there were less aluminum in the world, but it says there is only so much it can do about it.

Alcoa Inc., AA 0.24%traditionally the first out of the earnings season gate, is witnessing a seventh consecutive quarter of falling or flat raw aluminum prices on the London Metal Exchange, despite its own moves to curtail production.

The depressed raw aluminum price, which chiefly dents profit in the company's primary metals division, is the main reason company profit in the first quarter, to be announced on Monday, is expected to fall one cent to eight cents a share, even though many of Alcoa's biggest customers—makers of airplanes, cars and beverage cans—are either doing just fine or thriving.

And it might get worse before it gets better.

Speculators are busy shorting aluminum, part of a wide selloff in commodities, causing turmoil in the broader mining and metals sector. More than 20 mining CEOs have lost their jobs over the past 18 months. Massive mining projects are being suspended or put on hold. Inventories in warehouses are at record highs. Production in China, the chief source of global oversupply, is expected to increase a whopping 9% to 24.3 million metric tons this year. The LME price has dropped to under $1,900 per ton, down from over $2,500 two years ago, and more than $3,000 before the financial crisis.

Klaus Kleinfeld, Alcoa CEO since 2008, isn't sitting on his hands. He closed smelters and production lines, slashing annual production capacity by 531,000 metric tons in 2012, or 12% of the company's total. "We focus on the things that we can control to maximize value," he told analysts.

With low raw aluminum prices persisting despite these moves, Mr. Kleinfeld is trying to bolster profit by improving Alcoa's portfolio of products like screws, bolts and other high-value parts for the booming global aerospace industry, and sheets of metal for automobile makers looking to make vehicles lighter so that they consume less fuel. Income in its "engineered products and solutions" division rose 14% to $612 million in 2012, while income at its primary metals division, which makes raw aluminum, fell 36% to $309 million, a pattern expected to repeat itself in Monday's results.

The emphasis on making and selling more value-added products for cars and planes has helped Alcoa hold its own compared with its peers.Rio Tinto, another top-three aluminum maker, has announced total write-downs totaling $25 billion on Alcan, the Canadian aluminum business it bought in 2007.

Alcoa has been reducing production at its higher-cost facilities. One idea floated by shareholders and endorsed by some analysts as a way of maximizing value is selling its $10 billion raw aluminum business, whose profits are largely dependent on LME prices. But analysts say the company would have a hard time finding a buyer willing to pay what it wants, while prices are so low, which could lead to a fairly long wait.Prices aren't expected to rise until Europe, Japan and other pillars of the global economy get back on their feet, propelling global demand upward.

"For now, commodity funds in London are liquidating and dumping positions," says Lloyd O'Carroll, an analyst with Davenport & Co. of Richmond, Va., who has advocated selling off the raw aluminum division. "The chatter is quite negative, and it's hitting gold, oil, aluminum, everything."

Still, long term, some are optimistic. "The long-term future of aluminum is very strong," says Jorge Vazquez, an analyst for Chicago-based Harbor Intelligence. The aerospace industry is still growing as China, India and other emerging countries stock up on passenger jets. Around the world, governments are mandating better fuel-efficiency standards. The best way to achieve that is with aluminum, which is 25% to 35% lighter than steel. Sales of sheet aluminum are increasing 25% a year, says Mr. Vazquez.

For now, however, buyers fear overstocking, while supply remains plentiful. Companies—like Alcoa—have tried to cut production, but that's never enough, say analysts. "When there's oversupply, it always gets solved by higher demand, always, never by cutting supply, because not enough companies actually do it," says Mr. Vazquez.