United Technologies Corporation (UTC) was an American multinational conglomerate headquartered in Farmington, Connecticut. It researched, developed, and manufactured products in numerous areas, including aircraft engines, aerospace systems, HVAC, elevators and escalators, fire and security, building automation, and industrial products, among others. UTC was also a large military contractor, getting about 10% of its revenue from the U.S. government. In April 2020, UTC merged with the Raytheon Company to form Raytheon Technologies, later renamed RTX Corporation.

In 1974, Harry Jack Gray left Litton Industries to become the CEO of United Aircraft. He pursued a strategy of growth and diversification, changing the parent corporation's name to United Technologies Corporation (UTC) in 1975 to reflect the intent to diversify into numerous high tech fields beyond aerospace. (The change became official on May 1, 1975.) The diversification was partially to balance civilian business against any overreliance on military business. UTC became a mergers and acquisitions (M&A)–focused organization, with various forced takeovers of unwilling smaller corporations. The next year (1976), UTC forcibly acquired Otis Elevator. In 1979, Carrier Refrigeration and Mostek were acquired; the Carrier deal was forcible, while the Mostek deal was a white knight move against hostile takeover designs by Gould.

At one point, the military portion of UTC's business, whose sensitivity to "excess profits" and boom/bust demand drove UTC to diversify away from it, actually carried the weight of losses incurred by the commercial M&A side of the business. Although M&A activity was not new to United Aircraft, the M&A activity of the 1970s and 1980s was higher-stakes and arguably unfocused. Rather than aviation being the central theme of UTC businesses, high tech (of any type) was the new theme. Some Wall Street watchers questioned the true value of M&A at almost any price, seemingly for its own sake.

Mostek was sold in 1985 to the French electronics company Thomson.^{[citation needed]}

In 2007, UTC opened the Hawk Works, a Rapid Prototyping and Military Derivatives Completion Center (RPMDCC) located west of the Elmira-Corning Regional Airport in Big Flats, New York.

In March 2008, UTC made a $2.63 billion bid to acquire Diebold, a Canton, Ohio based manufacturer of banking and voting machines. Diebold rejected the buyout bid as inadequate.

In April 2010, UTC announced that it was investing €15 million ($20 million) to set up the United Technologies Research Centre Ireland at University College Cork’s Tyndall National Institute which would carry out research on energy and security systems.

In June 2012, it was discovered that UTC sold military technology to the Chinese. For pleading guilty to violating the Arms Export Control Act and making false statements, United Technologies and its subsidiaries were fined $75 million.