Toshiba Corporation (株式会社東芝 Kabushiki-gaisha Tōshiba?) (stylized as TOSHIBA) is a Japanese multinational engineering and electronics conglomerate corporation headquartered in Tokyo, Japan. Its products and services include information technology and communications equipment and systems, electronic components and materials, power systems, industrial and social infrastructure systems, consumer electronics, household appliances, medical equipment, office equipment, lighting, and logistics. Toshiba was founded in 1938 as Tokyo Shibaura Electric K.K. through the merger of Shibaura Seisaku-sho (founded in 1875) and Tokyo Denki (founded in 1890). The company name was officially changed to Toshiba Corporation in 1978. Toshiba has made numerous corporate acquisitions during its history, including of Semp in 1977, of Westinghouse Electric Company in 2006, of Landis+Gyr in 2011, and of IBM's point-of-sale business in 2012. Toshiba is organised into four business groupings: the Digital Products Group, the Electronic Devices Group, the Home Appliances Group and the Social Infrastructure Group. In 2010, Toshiba was the world's fifth-largest personal computer vendor measured by revenues (after Hewlett-Packard, Dell, Acer and Lenovo). In the same year, it was also the world's fourth-largest manufacturer of semiconductors by revenues (after Intel Corporation, Samsung Electronics and Texas Instruments). Toshiba is listed on the Tokyo Stock Exchange, where it is a constituent of the Nikkei 225 and TOPIX indices, the Osaka Securities Exchange, the Nagoya Stock Exchange and the London Stock Exchange.