Feb 24 (Reuters) - Wall Street’s main indexes opened lower on Wednesday, as high-flying growth stocks continued to be pressured by valuation concerns, while some cyclical stocks gained on prospects of an economic rebound. The Nasdaq Composite dropped 64.9 points, or 0.48%, to 13400.254 at the opening bell, falling for six out of the last seven sessions. The Dow Jones Industrial Average fell 37.6 points, or 0.12%, at the open to 31499.75, while the S&P 500 fell 7.7 points, or 0.20%, at the open to 3873.71. (Reporting by Devik Jain in Bengaluru; Editing by Shounak Dasgupta)