0000844779 2021-05-28 2021-05-28 0000844779 bf11:S000038448Member 2021-05-28 2021-05-28 pure iso4217:USD 0000844779 false 497 2021-01-31 N-1A <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">BLACKROCK FUNDS<sup style="font-size: 85%; vertical-align: top;">SM</sup></div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; text-align: center;">BlackRock Real Estate Securities Fund</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; text-align: center;">(the “Fund”)</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Supplement dated December 17, 2021</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">to the Fund’s Summary Prospectuses and Prospectuses, each dated May 28, 2021</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">A substantially similar version of this Supplement was previously filed on November 30, 2021.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">Effective January 1, 2022, the following change is made to the Fund’s Summary Prospectuses and Prospectuses:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Fund’s Prospectuses entitled “Fund Overview — Key Facts About BlackRock Real Estate Securities Fund — Performance Information” and the section of the Fund’s Summary Prospectuses entitled “Key Facts About BlackRock Real Estate Securities Fund — Performance Information” are supplemented as follows:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Effective January 1, 2022, the benchmark against which the Fund measures its performance will be changed from the MSCI U.S. REIT Index to the FTSE Nareit All Equity REITs Net Index. Fund management believes that the new benchmark is more representative of the sectors in which the Fund invests. The FTSE Nareit All Equity REITs Net Index is a free-float adjusted, market capitalization-weighted index of U.S. equity real estate investment trusts (“REITs”).</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">For the one year, five year and since inception (September 28, 2012) periods ended December 31, 2020, the average annual total returns for the FTSE Nareit All Equity REITs Net Index were ‑6.1%, 5.4%, and 7.0%, respectively.</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">BLACKROCK FUNDS<sup style="font-size: 85%; vertical-align: top;">SM</sup></div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; text-align: center;">BlackRock Real Estate Securities Fund</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; text-align: center;">(the “Fund”)</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">Supplement dated December 17, 2021</div> <div style="margin-top: 0pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold; text-align: center;">to the Fund’s Summary Prospectuses and Prospectuses, each dated May 28, 2021</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">A substantially similar version of this Supplement was previously filed on November 30, 2021.</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">Effective January 1, 2022, the following change is made to the Fund’s Summary Prospectuses and Prospectuses:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman; font-weight: bold;">The section of the Fund’s Prospectuses entitled “Fund Overview — Key Facts About BlackRock Real Estate Securities Fund — Performance Information” and the section of the Fund’s Summary Prospectuses entitled “Key Facts About BlackRock Real Estate Securities Fund — Performance Information” are supplemented as follows:</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">Effective January 1, 2022, the benchmark against which the Fund measures its performance will be changed from the MSCI U.S. REIT Index to the FTSE Nareit All Equity REITs Net Index. Fund management believes that the new benchmark is more representative of the sectors in which the Fund invests. The FTSE Nareit All Equity REITs Net Index is a free-float adjusted, market capitalization-weighted index of U.S. equity real estate investment trusts (“REITs”).</div> <div style="margin-top: 12pt; margin-bottom: 0pt; font-size: 10pt; font-family: times new roman;">For the one year, five year and since inception (September 28, 2012) periods ended December 31, 2020, the average annual total returns for the FTSE Nareit All Equity REITs Net Index were ‑6.1%, 5.4%, and 7.0%, respectively.</div> BLACKROCK FUNDSSM 2021-12-17 2021-05-28 2022-01-01