You won't find any clothes with Abercrombie & Fitch or American Eagle logos in Morgan Klein or Stephanie Friedman's closet anymore.
The twentysomethings prefer the fast fashion route these days—looking for trendy, less expensive clothes at retailers such as Bebe, H&M, and Forever 21.
"I feel Abercrombie is more preppy, and that's not what I wear anymore," said Klein, who worked at Abercrombie in her teens.
Friedman holds a similar view.
Sale sign in window of Abercrombie & Fitch storeStephanie Landsman | CNBC
"Everything says Abercrombie all over it, and I don't really like it," said Friedman. "If the logos weren't all over a lot of things, I would probably give it a try again. I think some of the fits are nice and the materials."
Wall Street is taking notice of teenagers and young adults shying away from brands that used to be a wardrobe staple. The so-called big "A" retailers, Abercrombie, Aéropostale and American Eagle, are slipping out of favor. These stocks are all down by double-digit percentages in the past six months, while the S&P 500 has risen 11.5 percent.
(Read more: Retailers' biggest problem right now? The sale bin )
"All you have to do is spend five minutes at an Abercrombie & Fitch and then walk across to an H&M. One striking difference is that Abercrombie is still selling clothes from 1995, but tailored," said Brian Sozzi, CEO and chief market strategist at Belus Capital Advisors. "H&M has a broader mix of very fashionable apparel at an unbeatable price."
H&M, which is part of a growing number of fast-fashion retailers, is adept at getting trends from the catwalk to the sales floor quickly, and at much cheaper prices. It's a practice traditional chain stores find challenging to adopt, as they place their orders much earlier than fast-fashion stores. For example, many traditional retailers place their holiday orders in April and May, while fast-fashion retailers' model allows them to order closer to the season.
(Read more: Anatomy of a markdown: What you are really paying)
"The shorter product lead time, basically from design to seeing it on the sales floor, entices the teen each time they are in the mall and online," Sozzi wrote in a research note on why traditional teen retailers are losing a war. "Kids nowadays don't want to be boxed into one look like a robot, they want to mix, match and standout."
