Shares of United Technologies, a Dow component, closed down 0.3 percent at $124.55.
Ackman told CNBC's Scott Wapner in February he had been building a stake in United Technologies, noting he thought the company was "great."
The 13F filing released Tuesday also revealed Pershing Square sold about 7.1 million shares of Mondelez, bringing his stake to 16.16 million shares. Ackman first bought into the company in 2015 with a massive $5.5 billion investment. The filings reflect holdings as of the end of the quarter, and holdings may have changed since then.