Shares of Block Inc. (XYZ) jumped over 8.5% in extended trading on July 18, 2025, following news that the fintech company will join the S&P 500 index, replacing Hess. The addition becomes effective before the opening bell on July 23, according to a statement from S&P Dow Jones Indices.Recent Changes to the S&P 500This marks the second alteration to the benchmark index last week. Earlier, ad-tech firm The Trade Desk was added to the S&P 500, taking the place of software company Ansys. The latter was acquired ...