June 27 (Reuters) - U.S. main stock indexes slipped at

open on Thursday as a slump in Micron after a lackluster

forecast weighed on some semiconductor stocks, while investors

parsed a string of economic data ahead of this week's crucial

inflation report.

The Dow Jones Industrial Average fell 20.70 points,

or 0.05%, at the open to 39,107.10. The S&P 500 opened

lower by 4.31 points, or 0.08%, at 5,473.59, while the Nasdaq

Composite dropped 11.20 points, or 0.06%, to 17,793.95

at the opening bell.