outside Sweden until after World War II. AB Volvo was introduced at the Stockholm Stock Exchange in 1935 and SKF then decided to sell its shares in the company. By 1942, Volvo acquired the Swedish precision engineering company Svenska Flygmotor (later renamed as Volvo Aero). Pentaverken, which had manufactured engines for Volvo, was acquired in 1935, providing a secure supply of engines and entry into the marine engine market. The first bus, named B1, was launched in 1934, and aircraft engines were added to the growing range of products at the beginning of the 1940s. Volvo was also responsible for producing the Stridsvagn m/42. In 1963, Volvo opened the Volvo Halifax Assembly plant, the first assembly plant in the company's history outside of Sweden in Halifax, Nova Scotia, Canada. In 1950, Volvo acquired the Swedish construction and agricultural equipment manufacturer Bolinder-Munktell. Bolinder-Munktell was renamed as Volvo BM in 1973. In 1979, Volvo BM's agricultural equipment business was sold to Valmet. Later, through restructuring and acquisitions, the remaining construction equipment business became Volvo Construction Equipment. In the 1970s, Volvo started to move away from car manufacturing to concentrate more on heavy commercial vehicles. The car division focused on models aimed at upper middle-class customers to improve its profitability. Partnerships and merging attempts In 1977, Volvo tried to combine operations with rival Swedish automotive group Saab-Scania, but the latter company rejected it. Between 1978 and 1981, Volvo acquired Beijerinvest, a trading company involved in the oil, food, and finance businesses. In 1981, those sectors represented about three quarters of the company revenue, while the automotive sector amounted for most of the rest. In the early 1970s, French manufacturer Renault and Volvo started to collaborate. In 1978, Volvo Car Corporation was spun off as a separate company within the Volvo group and Renault acquired a minority stake, before selling it back in the 1980s after a restructuring. In the 1990s, Renault and Volvo deepened their collaboration and both companies partnered in purchasing, research and development and quality control while increasing their cross-ownership. Renault would assist Volvo with entry-level and medium segment vehicles and in return, Volvo would share technology with Renault in upper segments. In 1993, a 1994 Volvo-Renault merger deal was announced. The deal was barely accepted in France, but it was opposed in Sweden, and the Volvo shareholders and company board voted against it. The alliance was officially dissolved in February