X0101 EFFECT 33 LIVE 2012-09-28 0001193125-12-404679 485APOS 0000844779 BLACKROCK FUNDS 033-26305 S000038448 BlackRock Real Estate Securities Fund C000118599 Investor A Shares S000038448 BlackRock Real Estate Securities Fund C000118600 Investor C Shares S000038448 BlackRock Real Estate Securities Fund C000118601 Institutional Shares