S&P Dow Jones Indices considers new index rules as mega IPOs loom

S&P Dow Jones Indices has launched a market consultation that could speed up how quickly mega-cap IPOs join its flagship benchmarks. Proposed changes include cutting the minimum public listing period for index eligibility from 12 to six months and potentially removing profitability requirements for large-cap firms. If adopted, the revisions (consultation open until May 28) could be tentatively implemented on June 8. Faster inclusion of potential listings like SpaceX, Anthropic and OpenAI would alter index composition, likely trigger sizeable passive flows and rebalances, and increase concentration risks — a shift other index providers such as Nasdaq and FTSE Russell are also racing to address.