NEW YORK ( Karvy Global) -- Base metals are trading higher on the Federal Reserve's decision to expand its asset purchases to boost the economy.A declining dollar index likely will increase investment demand for metals, especially precious metals. Additionally, narrowing inventory levels will continue to support higher metals prices. The copper inventory on the London Metal Exchange has hit 52-week lows at 350,250 tonnes, and the metal has risen to 31-month highs. Demand for copper will outstrip supply by 367,500 tonnes by 2011, according to median estimates of 12 analysts polled by Bloomberg, while the International Copper Study Group estimates a deficit of 435,000 tonnes during 2011. Meanwhile, aluminum producers may have to boost output by almost two-thirds to meet 5.3% demand growth over the next decade, Bloomberg reports, citing a statement by Rio Tinto ( RIO). In addition, the launch of new commodity ETFs will continue to boost metals stock prices. Given these fundamentals, metals stocks likely will continue to outperform broader markets in December. During November, the S&P 500 Index gained 3.7%, while the SPDR S&P Metals and Mining ETF ( XME) surged 9.1%. The following 10 stocks have high betas. In other words, they are more volatile than the stock market. That means they likely will outperform their peers in a rally. The stocks are listed from lowest beta value to highest. The 6-month charts on the following pages show the performance of each stock, along with the performance of the S&P 500, which is identified by the abbreviation INX.