Investor was dominated by Marcus Wallenberg, who remained chairman until he passed away in 1982. Toward the end of the 1960s, Saab and Scania-Vabis were merged in 1969.

In the beginning of the 1970s, Stockholms Enskilda Bank and Skandinaviska Banken merged. The portfolio management company Export-Invest was formed.

In 1971, Investor also got its fourth CEO, Carl de Geer, who remained CEO for seven years.

Forestry holdings and retailing
The 1970s involved several significant events for Investor. During this era Investor was a major shareholder in a number of forestry companies: Stora Kopparberg, Bergvik & Ala, Papyrus and Kopparfors. Jacob Wallenberg was chairman of the first two, and Marcus Wallenberg of the latter two.

The first big event was in 1975, when Papyrus bought Kopparfors, and later the same year, Stora Kopparberg acquired Bergvik & Ala. Two major mergers took place in 1976 as well. Investor was the largest shareholder of the Swedish retail chain NK, and Carl de Geer was chairman of NK. In the beginning of 1976, NK and Åhléns merged to form NK-Åhléns to become the largest private mercantile partnership in Scandinavia with 200 department stores and 23,000 employees. The marriage ended in divorce after four years, and in 1980, the five department stores of NK were separated again.

Investor and the shipping industry
1976 was an eventful year in the shipping industry as well. Investor had a substantial interest in Svenska Ostasiatiska Kompaniet, chaired by Carl de Geer, and in Motortank.

Discussions were initiated in 1976 to merge with a third party, the Tirfing Group, which also had stakes in Svenska Ostasiatiska Kompaniet. Tirfing was in poor financial condition and needed a consolidation to survive. The discussions led to a merger between Tirfing, Ostasiatiska Kompaniet and Motortank in 1978. The new shipping company assumed the name of Broströms Rederi AB.