Bill Ackman's Pershing Square Capital Management has disclosed an almost 20% stake in Hertz Global Holdings, prompting a dramatic surge of more than 56% in the car rental company's share price, according to a report by Bloomberg.

The company's record one-day gain came after regulatory filings revealed the hedge fund had acquired 12.7 million shares valued at approximately $46.5m. CNBC later reported the total exposure, including swaps, amounts to a 19.8% stake, positioning Pershing Square as Hertz’s second-largest shareholder.

The move marks a potential vote of confidence in a company still working to recover from a string of missteps, including a controversial push into electric vehicles. Hertz's aggressive pivot to Tesla EVs proved problematic, with customers put off by charging logistics and maintenance costs running higher than expected. The firm has since been shifting its strategy and revamping its fleet.

Hertz, which emerged from bankruptcy in 2021, had seen its stock slump by 47% over the past year prior to the news. Ackman’s investment has reignited investor interest and could hint at future activist engagement or a strategic turnaround effort — familiar territory for Pershing Square.

Neither Hertz nor Pershing Square provided immediate comment on the development.