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Navient, Under Armour joining S&P 500 index

NEW YORK (AP) -- Athletic clothing and gear maker Under Armour and Navient, which is being spun off from Sallie Mae, will join the S&P 500 index on Wednesday.

S&P said Under Armour Inc. and Navient Corp. will replace Beam Inc., the maker of Jim Beam and Maker's Mark, and Sallie Mae itself on the S&P 500. Navient is Sallie Mae's loan management, servicing and asset recovery division. The spinoff of Navient is expected to close Wednesday.

Beam is being removed from the index because it is being acquired by Japanese liquor company Suntory Holdings.

Sallie Mae is officially known as SLM Corp. It will be added to the S&P's MidCap 400 index to reflect its decreased size. PolyOne Corp., which makes resins used in plastic pipe and other products, will also be added to the MidCap index.

The smallest company on the MidCap 400 index, coal producer Alpha Natural Resources Inc., will be removed.

Aceto Corp., which distributes chemicals and generic drugs, will replace PolyOne on the S&P SmallCap 600 index.