In 1932, just before the Kreuger Trust collapsed, and the years after it, the Wallenberg sphere increased its holding in SKF, added a minority stake in LM Ericsson and acquired a large interest in STAB (Svenska Tändsticksaktiebolaget) (known as Swedish Match today).

The roller bearing manufacturer SKF was the largest holding in the Investor portfolio at the time. Jacob Wallenberg was elected to the company's board of SKF's directors in 1934, and by the time World War II was over, the sphere's interest constituted 11 percent of SKF's voting rights.

During the war, Marcus Wallenberg Sr. passed away in 1943 and Johannes Hellner took over as chairman of the bank and Investor. In 1945, Jacob Wallenberg took over as chairman of Investor's board.

First CEO, the 1960s and Incentive for new science and technologies
In 1949, Investor elected its first CEO, Frans G. Liljenroth. Rolf Calissendorff from Stockholms Enskilda Bank became Investor's second CEO the year after, in 1950, when Liljenroth retired. During Calissendorffs' sixth and last year as CEO, in 1956, Investor acquired shares in Electrolux after one of the company's principal founders and owners, Axel Wenner-Gren, contacted Marcus Wallenberg with an offer to buy a dominant stake. Electrolux remains a large core investment today. In 1957, when Rolf Calissendorff retired, Walter Wehtje succeeded him as CEO of Investor.

In 1963, Incentive was established to acquire and develop small, technology-oriented businesses, illustrating Marcus Wallenberg's idea to create companies for the promotion of science and technology. Incentive's shares were sold out two hours after the company was introduced on the market. Investor was one of the first to subscribe.