(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%.

(Reporting by Zaheer Kachwala in Bengaluru; Editing by Shinjini Ganguli)