The new formula is publicly available, but to sell tenofovir, companies must be licensed by Gilead Sciences Inc.

WSJ: Researchers Manipulate HIV Drug's Chemistry to Lower Cost

The companies that experienced the reductions are: Gilead Sciences Inc. ( GILD), Biogen Idec Inc. ( BIIB), Pall Corp. ( PLL), Onyx Pharmaceuticals ( ONXX) and Regeneron Pharmaceuticals ( REGN).

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Among the largest underlying components of IVW, in trading today Visa Inc ( NYSE: V) is trading flat, Gilead Sciences, Inc. ( NASD: GILD) is up about 0.3%, and Verizon Communications Inc ( NYSE: VZ) is higher by about 0.3%.

FORBES: iShares S&P 500 Growth Index Fund Experiences Big Outflow