Pershing Square Capital Management, the investment firm run by investing guru Bill Ackman (Trades, Portfolio), trimmed its stake in Chipotle Mexican Grill Inc. (CMG, Financial) by nearly 10% during the first quarter of 2024. However, the restaurant chain remains the firm's largest holding at just over 20% of its total portfolio.Chipotle has been a longtime favorite of Ackman as the firm made its initial investment in late 2016. Since then, shares have delivered a total return of roughly 620%. Comparably, th ...