Jan 8 (Reuters) - The Dow opened lower on Monday, hurt by a tumble in Boeing shares following the grounding of some its jets, while megacap stocks lifted the S&P 500 and the Nasdaq.

The Dow Jones Industrial Average fell 138.74 points, or 0.37%, at the open to 37,327.37.

The S&P 500 opened higher by 6.46 points, or 0.14%, at 4,703.70, while the Nasdaq Composite gained 40.39 points, or 0.28%, to 14,564.47 at the opening bell. (Reporting by Ankika Biswas in Bengaluru; Editing by Devika Syamnath)