Ignore the perennial distraction of Russian oligarch turf battles that have defined Rusal’s life as a listed company. Consider instead the investment case for the world’s biggest producer of aluminum. Subdued industry demand for the white metal has depressed the London Metal Exchange price by a 10th during the past year. But the market is distorted by two things. Low interest rates have meant that financial demand accounts for nearly three-quarters of trading volume, Rusal estimates. And China, accounting for two-fifths of global demand, has also skewed the market by increasing output from new and once-idled plants kept alive only by government grants.