Bill Ackman runs Pershing Square, an activist overseeing $15.53B in disclosed equity holdings (SEC CIK 0001336528). The latest portfolio (2025Q4) discloses 11 positions across 6 sectors, with the largest positions in BN, UBER and AMZN. On a mark-to-market basis the tracked portfolio has returned 115.0% since 2016Q1. OpenStocks tracks 40 consecutive quarterly snapshots for this manager — every position change, new entry, and exit is logged below.