Aug 15 (Reuters) - The blue-chip Dow opened at a record

high on Friday, as UnitedHealth's shares jumped after Berkshire

Hathaway raised its stake in the health insurer, while

expectations of an interest rate cut in September also lifted

the mood.

The Dow Jones Industrial Average rose 248.7 points,

or 0.55%, at the open to 45,159.91. The S&P 500 rose 8.8

points, or 0.14%, at the open to 6,477.38​, while the Nasdaq

Composite dropped 1.3 points, or 0.01%, to 21,709.336 at

the opening bell.

(Reporting by Sanchayaita Roy; Editing by Devika Syamnath)