Blockbusting was a common real estate tactic used to convince white housing owners to sell their property cheaply by using their fear of African-Americans moving into their neighborhood and thereby causing property values to fall. After the owners sold their homes, the real estate agent would sell the same home to African-Americans at an inflated price.
Wikipedia
Blockbusting
Video
Bigotry and Blockbusting in Baltimore
Further Reading
A Requiem for Blockbusting: The Campaign Against Black Wealth in American Housing (Medium)
A Requiem for Blockbusting: Law, Economics, and Race-Based Real Estate Speculation (Fordham Law Review)
Blockbusting (Blackpast.org)
Racial Restriction and Housing Discrimination in the Chicagoland Area (Lake Forest College)