Vanguard Group is extending its Admiral low-cost shares to six additional domestic equity index funds, effective September. The new fees will range from 10 basis points to 21 basis points.

“The introduction of additional Admiral Shares is another example of our long-term commitment to reduce the cost of investing for our clients,” said Bill McNabb, chairman and CEO of Vanguard.

Vanguard first introduced the Admiral Shares in November 2000 and in October 2010 lowered the account balance minimums to qualify for the lower-cost shares from $100,000 to $10,000.

With this move, Vanguard will offer Admiral Shares on 75 of its funds.

In addition, Vanguard is lowering the expense ratios on the institutional shares for the Vanguard Intermediate-Term Bond Index Fund to 5 basis points and for the Vanguard Long-Term Bond Index Fund to 7 basis points.