In recent years, many teen apparel retailers have filed for bankruptcy due to declining mall traffic, competition from e-tailers and fast-fashion retailers, and shifting teen tastes. However, more resilient apparel retailers have survived by closing stores, expanding their e-commerce initiatives, and launching fresh brands.Piper Jaffray recently released its 35th semiannual "Taking Stock with Teens" survey of 6,000 teen shoppers across the U.S.