For many investors with long memories, zinc and the companies that mine it, are to be voided at all costs. It's a sector that has proven problematic for various reasons, dating back to companies like Pasminco in the 1990s. Quite simply, it's not easy to consistently turn a profit in the zinc business. But times are changing. Zinc has firmed by 43% this year from its January lows, reinforcing its position as the market's best-performing metal. It's also recorded its best quarterly performance since 2010. The primary catalyst relates to concerns that the much-anticipated zinc supply crisis might finally be upon us. RBC Capital Markets forecasts that zinc output of zinc will trail demand by 144,000 tons during 2016, and will continue to remain in deficit until at least 2020. The closure of two of the world’s biggest mines - Century and Lisheen - have been major catalysts for the change in market fundamentals. On the demand side, expectations of further central bank stimulus is also boosting the metal's prospects. Zinc is no longer a four-letter word for investors.