Electrolux AB (ɛˈlɛ̂kːtrʊˌlɵks, ɛlɛktrʊˈlɵks) is a Swedish multinational home appliance manufacturer, headquartered in Stockholm. It is consistently ranked the world's second largest appliance maker by units sold, after Whirlpool. Electrolux products sell under a variety of brand names (including its own), and are primarily major appliances and vacuum cleaners intended for home consumer use. Electrolux has a primary listing on the Stockholm Stock Exchange and is a constituent of the OMX Stockholm 30 index. The company originates from a merger of two companies—Lux AB and Svenska Elektron AB, the former an established manufacturer and the latter a younger company founded by a former vacuum salesman who had also been an employee of the former firm. The origins of Electrolux are closely tied to the vacuum, but today it also makes major appliances. Electrolux made an initial public offering on the London Stock Exchange in 1928 (it was delisted in 2010) and another on the Stockholm Stock Exchange in 1930. its shares trade on the NASDAQ OMX Nordic Market and over-the-counter. Electrolux is an OMX Nordic 40 constituent stock. In 1919, a Svenska Elektron AB acquisition, Elektromekaniska AB, became Elektrolux (the spelling was changed to Electrolux in 1957). It initially sold Lux branded vacuum cleaners in several European countries. In 1923, the company acquired AB Arctic and subsequently added absorption refrigerators to its product line. Other appliances soon followed, including washing machines in 1951, dishwashers in 1959, and food service equipment in 1962. The company has often and regularly expanded through mergers and acquisitions. While Electrolux had bought several companies before the 1960s, that decade saw the beginnings of a new wave of M&A activity. The company bought ElektroHelios, Norwegian Elektra, Danish Atlas, Finnish Slev, and Flymo, et al., in the nine years from 1960 to 1969. It sold its American subsidiary to Consolidated Foods in 1968, exiting the American market until 1974, when Electrolux acquired Eureka-Williams from National Union, one of the oldest names in the vacuum cleaner industry.