Garmin Ltd., a maker of navigation devices, will join the benchmark S&P 500 index after the close of trading on Dec. 11.
Garmin is replacing R.R. Donnelley, which is moving to the MidCap 400 index.
Standard & Poor's said Wednesday that R.R. Donnelley & Sons Co. is replacing Medicis Pharmaceutical, which is being acquired by Valeant Pharmaceuticals International Inc.
R.R. Donnelley, which provides integrated communications services, has a market cap of about $1.68 billion. Garmin's market cap is about $7.78 billion.
Garmin shares added 4.5 percent, or $1.79, to $41.50 in after-hours trading following the announcement. The stock ended the regular session down 19 cents at $39.71.
Stocks typically gain when they added to major indices because mutual funds and other institutional investors that track those indices are expected to update their portfolios by purchasing shares of the newly added companies.
Donnelly shares lost 6 cents to $9.24 in extended trading.