Exhibit 99.1350CERT

         Certification Pursuant to Rule 30a-2(b) under the 1940 Act and
                      Section 906 of the Sarbanes Oxley Act

Pursuant to 18 U.S.C. ss. 1350, the undersigned officer of BlackRock S&P 500
Index Fund of BlackRock Index Funds, Inc. and Master S&P 500 Index Series of
Quantitative Master Series LLC (the "Registrant"), hereby certifies, to the best
of his knowledge, that the Registrant's Report on Form N-CSR for the period
ended December 31, 2007, (the "Report") fully complies with the requirements of
Section 15(d) of the Securities Exchange Act of 1934, as amended, and that the
information contained in the Report fairly presents, in all material respects,
the financial condition and results of operations of the Registrant.

Date: February 21, 2008


/s/ Donald C. Burke
-------------------
Donald C. Burke
Chief Executive Officer (principal executive officer) of
BlackRock S&P 500 Index Fund of BlackRock Index Funds, Inc. and
Master S&P 500 Index Series of Quantitative Master Series LLC

Pursuant to 18 U.S.C. ss. 1350, the undersigned officer of BlackRock S&P 500
Index Fund of BlackRock Index Funds, Inc. and Master S&P 500 Index Series of
Quantitative Master Series LLC (the "Registrant"), hereby certifies, to the best
of his knowledge, that the Registrant's Report on Form N-CSR for the period
ended December 31, 2007, (the "Report") fully complies with the requirements of
Section 15(d) of the Securities Exchange Act of 1934, as amended, and that the
information contained in the Report fairly presents, in all material respects,
the financial condition and results of operations of the Registrant.

Date: February 21, 2008


/s/ Neal J. Andrews
-------------------
Neal J. Andrews
Chief Financial Officer (principal financial officer) of
BlackRock S&P 500 Index Fund of BlackRock Index Funds, Inc. and
Master S&P 500 Index Series of Quantitative Master Series LLC

This certification is being furnished pursuant to Rule 30a-2(b) under the
Investment Company Act of 1940, as amended, and 18 U.S.C. Section 1350 and is
not being filed as part of the Form N-CSR with the Securities and Exchange
Commission.