The Raytheon Company was a major U.S. defense contractor and industrial corporation with manufacturing concentrations in weapons and military and commercial electronics. It was previously involved in corporate and special-mission aircraft until early 2007. Raytheon was the world's largest producer of guided missiles. In April 2020, the company merged with United Technologies Corporation to form Raytheon Technologies. Established in 1922, the company reincorporated in 1928 and adopted its present name in 1959. During 2018, the company had around 67,000 employees worldwide and annual revenues of approximately US$25.35 billion. More than 90% of Raytheon's revenues were obtained from military contracts and, as of 2012, it was the fifth-largest military contractor in the world. , it was the third largest defense contractor in the United States by defense revenue. In 2003, Raytheon's headquarters moved from Lexington, Massachusetts, to Waltham, Massachusetts. The company had previously been headquartered in Cambridge, Massachusetts, from 1922 to 1928, Newton, Massachusetts, from 1928 to 1941, Waltham from 1941 to 1961 and Lexington from 1961 to 2003. History Early years In 1922, two former Tufts University School of Engineering, roommates Laurence K. Marshall and Vannevar Bush, along with scientist Charles G. Smith, founded the American Appliance Company in Cambridge, Massachusetts. Its focus, which was originally on new refrigeration technology, soon shifted to electronics. The company's first product was a gaseous (helium) voltage-regulator tube that was based on Charles Smith's earlier astronomical research of the star Zeta Puppis. The electron tube was christened with the name Raytheon (a compound of Old French and Greek meaning 'light from the gods') and was used in a battery eliminator, a type of radio-receiver power supply that plugged into the power grid in place of large batteries. This made it possible to convert household alternating current to a regulated, high voltage direct current for radios and thus eliminate the need for expensive, short-lived batteries. In 1925, the company changed its name to Raytheon Manufacturing Company and began marketing its rectifier, under the Raytheon brand name, with commercial success. In 1928 Raytheon merged with Q.R.S. Company, an American manufacturer of electron tubes and switches, to form the successor of the same name, Raytheon Manufacturing Company. By the 1930s, it had already grown to become one of the world's largest vacuum tube manufacturing companies. In 1933 it diversified by acquiring Acme-Delta Company, a producer of transformers, power equipment, and electronic auto parts. During World War II