Sept 6 (Reuters) - The S&P Dow Jones Indices said on

Friday server maker Dell Technologies ( DELL ), data analytics

firm Palantir Technologies ( PLTR ) and property and casualty

insurer Erie Indemnity ( ERIE ) will join the benchmark S&P 500

before the market opens on Sept. 23.

Shares of Palantir ( PLTR ) rose nearly 8% in extended trading, while

those of Dell and Erie rose 6% and 3%, respectively.

The three companies will replace American Airlines Group ( AAL )

, online marketplace Etsy ( ETSY ) and diagnostics

company Bio-Rad Laboratories ( BIO/B ) in the index.

Shares of American Airlines ( AAL ) were down 0.7%, while those of

Bio-Rad Laboratories ( BIO/B ) and Etsy ( ETSY ) fell about 1%.