For some investors, earnings season is the highlight of each quarter. This is the six-week period where most S&P 500 companies report their quarterly operating results, which gives investors a good bead on the health of corporate America and Wall Street.
But an argument can be made that the quarterly filing of Form 13Fs with the Securities and Exchange Commission is equally valuable to the investing community. A 13F provides a snapshot of which stocks Wall Street's brightest investment minds (with at least $100 million in assets under management) were buying and selling in the most recent quarter. In other words, it's a concise way of figuring out which stocks, industries, sectors, and trends have the attention of the stock market's greatest investors.
Although Berkshire Hathaway's billionaire CEO Warren Buffett tends to be the most-followed of all top-tier asset managers, he's not the only prominent fund manager known for their investing prowess. Pershing Square Capital Management's Bill Ackman is another billionaire investors have learned to play close attention to.
Image source: Getty Images.
Ackman is an activist investor who tends to run a fairly concentrated portfolio (often around a dozen holdings) at Pershing Square, with nearly $12 billion in assets under management at the end of March 2025. Activist investors usually take sizable stakes in public companies with the purpose of effecting change that unlocks value for shareholders. This might entail winning seats on a company's board, encouraging acquisitions or divestments, boosting capital-return programs, or suggesting operational changes/improvements.
For the past seven years, Pershing Square's billionaire chief has been a fairly persistent seller of Chipotle Mexican Grill (CMG 0.35%) stock, but has absolutely piled into an industry-leading company whose global addressable market can grow by almost 950% by 2033.
Ackman has been chopping his fund's Chipotle stake for seven years
Dating back to the fourth quarter of 2016, Chipotle Mexican Grill has represented a top-four holding by market value in all but two quarters for Pershing Square Capital Management. One of those two quarters happens to be the first quarter of 2025.
Taking into account that Chipotle conducted a historic 50-for-1 forward split a little over a year ago, Ackman's fund held the equivalent of 144,123,150 shares of the company as of June 30, 2018. But as of March 31, 2025, this position had been whittled down to 21,541,177 shares.
NYSE: CMG
Key Data Points
One very logical reason that may help explain why billionaire Bill Ackman has green-lit the sale of 85% of Pershing Square's peak stake in Chipotle is the company's outperformance. Activist investors seek to unlock value; and since the midpoint of 2018, shares of Chipotle Mexican Grill have gained 562%, through the closing bell on July 3, 2025. There's no shame in locking in triple-digit gains, especially for a stock that's outperformed the benchmark S&P 500 by 431 percentage points since mid-2018.
Another potential catalyst behind Ackman's fairly persistent selling of Chipotle stock is the company's valuation.
On one hand, Chipotle has earned itself a premium among restaurant stocks thanks to its innovation (e.g., the introducing of mobile order lanes known as "Chipotlanes") and reliance on fresh food. It's shunned freezers in favor of fresh local produce (when possible) and responsibly raised meats that are free from unnecessary antibiotics. Consumers have demonstrated a willingness to pay more for higher quality food.
But there's only so much innovation restaurants can squeeze from their product line. Chipotle is currently tipping the scales at a forward price-to-earnings (P/E) ratio of 40, which is quite high considering the company's recent slowdown in comparable restaurant sales.
Inflationary concerns may also be creeping into the picture. Although Chipotle has successfully passed along higher prices to its customers in the past, a reported decline of 0.4% in comparable restaurant sales in the March-ended quarter suggests consumer wallets are stretched. While the average check did climb 1.9% in the first quarter, total transactions declined by 2.3%.
There doesn't appear to be much in the way of value for Ackman or his team to squeeze out of Chipotle Mexican Grill stock at this point.
Image source: Getty Images.
Billionaire Bill Ackman piled into this industry leader during the first quarter
On the other end of the spectrum is an industry-leading company that Pershing Square's billionaire investor has lavished with praise this year. I'm talking about Uber Technologies (UBER 0.81%), which is best-known for its ride-sharing operations, but also encompasses food delivery, advertising services, and a freight logistics network.
Through the first three months of 2025, Ackman oversaw the acquisition of 30,301,161 shares of Uber, which made this ride-sharing kingpin the largest holding in Pershing Square Capital Management's investment portfolio (almost 19% of invested assets).
The addressable market for ride-sharing is one of the more obvious reasons Ackman was likely attracted to Uber. Keeping in mind that forecasts remain very fluid, Stratis Research foresees the global addressable market for ride-sharing climbing from $87.7 billion in 2025 to an estimated $918.2 billion by 2033. If this projection is remotely in the ballpark, it would mean the worldwide addressable market would more than 10X over the coming eight years. This is a huge opportunity for Uber.
Uber's management team marks another reason Ackman is bullish on the company. Pershing Square's billionaire chief has previously proclaimed, "Since he joined the company in 2017, Dara Khosrowshahi CEO has done a superb job in transforming the company into a highly profitable and cash-generative growth machine." Just as Warren Buffett has preached the importance of consumer trust in businesses, Ackman fully believes that Uber is being steered in the right direction by its existing leadership.
NYSE: UBER
Key Data Points
When Bill Ackman piled into Uber during the first quarter, he also pointed to the company's attractive valuation. In a post on social platform X (formerly Twitter), Ackman suggested, "Remarkably, it [Uber] can still be purchased at a massive discount to its intrinsic value."
But things have changed a bit since Ackman entered his position in Uber earlier this year. Shares of the company are now valued at a somewhat aggressive forward P/E ratio of 27. Moreover, Uber is valued at a price-to-sales ratio of 4.4, which is approximately four times higher than that of chief domestic rival Lyft.
Understandably, there's more to this comparison than just sales. As noted, Uber is the undisputed market share leader in ride-sharing in the U.S., with Lyft a distant second. But is this worth a price-to-sales ratio premium that's 300% higher than Lyft? A reasonable argument can be made that the answer is no, especially with new ride-share competition entering the arena.
Bill Ackman's success as an Uber Technologies investor will likely be determined by how well Uber handles new competition and what steps it takes to retain its premium pricing power.
