Vanguard, the No. 3 U.S. exchange-traded fund sponsor by assets under management, today is shifting indexes on four U.S.-focused ETFs to benchmarks created by University of Chicago-linked CRSP from MSCI Inc. in the latest phase of implementation of its big index-change announcement on Oct. 2.

The funds in question, and the index changes, were detailed today in a New York Stock Exchange electronic communique as follows:

• Vanguard Mega Cap ETF (NYSEArca: MGC), which will now be based on the CRSP US Mega Cap Index. The new benchmark replaces the MSCI US Large Cap 300 Index, and the fund will drop its previous name, the Vanguard Mega Cap 300 ETF
• Vanguard Large-Cap ETF (NYSEArca: VV), which will now be based on the CRSP US Large Cap Index. The new benchmark replaces the MSCI US Prime Market 750 Index, and the fund’s name isn’t changing
• Vanguard Mid-Cap ETF (NYSEArca: VO), which will now be based on the CRSP US Mid Cap Index. The new benchmark replaces the MSCI US Mid Cap 450 Index, and the fund’s name isn’t changing
• Vanguard Small-Cap ETF (NYSEArca: VB), which will now be based on the CRSP US Small Cap Index. The new benchmark replaces the MSCI US Small Cap 1750 Index, and the fund’s name isn’t changing.

Vanguard shook up the world of index investment early last autumn when it said it was dropping MSCI indexes on 22 funds, including the four above and—most conspicuously—the benchmark on its huge $61 billion Vanguard FTSE Emerging Markets Index ETF (NYSEArca: VWO). The Valley Forge, Pa.-based company said the changes were designed to save investors money over the long term.

Of the 22 funds undergoing index changes, 16 are U.S.-focused portfolios—including the above four—and are shifting to benchmarks from CRSP. The other six, like VWO, are internationally focused portfolios that will be transitioning to benchmarks created by FTSE.

VWO has already undergone a name change, but is still in the midst of a change to its new FTSE index. The fund is now being organized around a transitional index that was created to better manage the unwinding of a sizable position the MSCI-conceived iteration had in South Korean equities.

That position was at 15 percent of the MSCI-based fund, while the new FTSE Emerging Markets Index doesn’t include South Korea because FTSE doesn’t classify the vibrant Asian nation that is home to global consumer brands such as Samsung, Hyundai and Kia as a developing country.

Vanguard officials have previously said that announcements related to the various index changes would be promulgated as they unfold.