Core Insights - Robinhood's share price surged nearly 16% following its announcement of joining the S&P 500 Index, surprising even its CEO, Vlad Tenev [1][2] - The inclusion in the S&P 500 leads to significant buying activity from ETFs and institutional investors, which contributes to the stock price increase [4] Company Announcement - CEO Vlad Tenev expressed excitement about Robinhood's inclusion in the S&P 500, but he learned about the news through an S&P press release, just like the rest of the market [2] Market Reaction - The stock price increase for Robinhood mirrors similar trends observed with other companies like DoorDash and Coinbase that joined the S&P 500 this year [3] Index Composition - The S&P 500 Index is rebalanced periodically, with new companies added and others removed, often due to mergers or committee discretion [6] - The committee responsible for these decisions is secretive, with members not disclosed to prevent lobbying [7] Historical Context - Howard Silverblatt, a senior index analyst at S&P Dow Jones, has witnessed significant changes in the index over the past 49 years, including a shift towards more tech and IT firms [5]

Core Viewpoint - S&P Dow Jones Indices did not make any changes to the S&P 500 index, marking the first quarterly rebalance without any stock changes since March 2022 [1] Group 1 - Robinhood (HOOD) and AppLovin (APP) were not added to the S&P 500 index despite analysts' expectations [1] - The decision reflects a continuation of the current index composition without any additions or deletions [1]