Oct 31 (Reuters) - Wall Street's main indexes opened

lower on Thursday as warnings from Meta Platforms and Microsoft

about rising AI costs sobered some of the buzz around megacap

stocks, which have been the market's primary driver this year.

The Dow Jones Industrial Average fell 185.2 points,

or 0.44%, at the open to 41956.34. The S&P 500 fell 38.3

points, or 0.66%, at the open to 5775.34​, while the Nasdaq

Composite dropped 180.6 points, or 0.97%, to 18427.31 at

the opening bell.