On December 31, 2023, PRIMECAP Management (Trades, Portfolio) executed a significant stock transaction involving Mattel Inc (NASDAQ:MAT), a renowned toy manufacturer. The firm decided to reduce its holdings in Mattel, signaling a shift in its investment strategy regarding the toy company. This move by PRIMECAP Management (Trades, Portfolio), a firm known for its value-driven investment approach, has caught the attention of investors and market analysts alike, prompting discussions about the implications for Mattel's stock and PRIMECAP's portfolio.