Quarterly filings from billionaire investors including Warren Buffett and Bill Ackman reveal their latest investments and what stocks they're adding to or selling from current positions. In the fourth quarter of 2025, the two well-known billionaires differed drastically on one Magnificent Seven stock.

Ackman Adds to Amazon Holdings, Buffett Trims Back Stake

The fourth quarter 13F from Berkshire Hathaway (NYSE:BRK)(NYSE:BRK) was the last with Buffett as CEO of the conglomerate.

The filing revealed that Berkshire trimmed its stake in Amazon.com Inc (NASDAQ:AMZN) by 77%, selling 7,724,000 shares of the Magnificent Seven stock in the fourth quarter. Berkshire ended the quarter with 2,276,000 AMZN shares owned.

Pershing Square, led by Ackman, made a reverse move in the fourth quarter. The hedge fund disclosed increasing its Amazon position by 65%, adding 3,786,508 shares in the fourth quarter.

With Amazon shares down $18.58 each, or 8%, since the closing price on Dec. 31, 2025, Buffett is the investor who has so far made the right decision and saved his investors from more losses.

By selling the 7,724,000 AMZN shares in the fourth quarter, Buffett saved investors $143,511,920 based on the closing price on Dec. 31, 2025 and the price at the time of writing ($212.24).

Berkshire's remaining Amazon holdings are down $42,288,080 since the end of the fourth quarter, but the timely sale saved more losses based on the current share price.

Ackman on the other hand may regret the timing of his Amazon purchase. While it is unknown exactly when he boosted the size of the stake for Pershing Square Capital, the added Amazon shares in the fourth quarter are down in the months since.

Based on the current AMZN share price and the Dec. 31, 2025 closing price, the 3,784,508 shares added by Ackman in the fourth quarter are down $70,316,158.64 in 2026.

All seven Magnificent Seven stocks are down year-to-date in 2026 with Amazon one of the better performers of the seven. This comes after Amazon was the worst-performing of the seven stocks in 2025, with a gain of 4.8%.

Ackman, Buffett Differ On Magnificent Seven Top Picks

Amazon is not the only Magnificent Seven stock owned by Berkshire Hathaway and Pershing Square Capital.

Berkshire Hathaway has owned Apple Inc (NASDAQ:AAPL) stock for many years and the tech giant was the top holding at the end of the fourth quarter at 23% of assets in the investment portfolio. Berkshire sold around 4% of their Apple stock in the fourth quarter. Apple stock is down 6.5% year-to-date in 2026.

Alphabet Inc (NASDAQ:GOOGL) was the 10th largest holding in Berkshire Hathaway at the end of the fourth quarter. The lowered position in Amazon stock took that Magnificent Seven stock down to 27th place among Berkshire Hathaway holdings at the end of the fourth quarter.

In the Pershing Square investment portfolio, Amazon was the third-largest holding at the end of the fourth quarter. Alphabet Class C (NASDAQ:GOOG) and Class A shares ranked fourth and ninth at the end of the fourth quarter.

Pershing Square lowered its stake in both Alphabet share classes, reducing its GOOG position by 2% and its GOOGL position by 86%.

A new position in Meta Platforms (NASDAQ:META) was disclosed by Ackman in the fourth quarter, and the stock was the fifth largest holding at the end of the year.

With Buffett no longer the CEO of Berkshire Hathaway, the holdings of the conglomerate could quickly change in 2026. Investors will be closely following to see which Magnificent Seven stocks remain in the investment portfolio.

For Ackman, the new bet on Meta Platforms has struggled in 2026, alongside the increased Amazon stake. The next 13F filing could indicate whether these two stocks are still top bets for the hedge fund leader.

Image created using artificial intelligence via Gemini.