Juul's e-cig has lost tremendous market share since it became the focus of the Food and Drug Administration's campaign against teenagers vaping. Where it once held 75% of the market, Juul is now in second place with a 29% share, and fading behind British American Tobacco 's ( BTI -0.36% ) Vuse brand. True, the federal appeals court did order the agency to review Juul's application again, but the damage has already been done.