Coty COTY.N gained 5.1% after the CoverGirl parent hiked its annual core sales forecast. By Stephen Culp Sept 20 (Reuters) - Wall Street oscillated after the U.S. Federal Reserve held key interest rates unchanged as widely expected, and revised economic projections higher, even as Chairman Powell warned the battle against inflation was far from over. All three major U.S. stock indexes whipsawed in the wake of announcement and the accompanying Summary Economic Projections (SEP) and dot plot, which sees an additional 25 basis point rate hike this year, peaking in the 5.50%-5.75% range.