Twenty-five of the biggest tech companies in the world, including Amazon.com Inc., Alphabet, Tesla and Netflix share one major investor, Softbank Group Corp, which has built a stake in those companies valued at nearly $4 billion.

All of Softbank's largest investments are in tech giants based in the United States, records from a U.S. Securities and Exchange Commission filing on Monday showed.

The Japanese multinational holding firm's biggest investment is in Amazon stocks, valued  at $1.04 billion. Next is Alphabet at $475 million, followed by Adobe Inc. at $248.6 million, Netflix at almost $190 million, and Tesla at nearly $123 million. 

During an earnings call, Softbank Chief Executive Officer Masayoshi Son unveiled a new asset management venture last week that will help the company allocate excess money from big-ticket divestment of assets into liquid stocks. The Tokyo-based conglomerate has already shelled out roughly $10 billion in share acquisitions.

Softbank also has a $183 million investment in Microsoft, $112 million in PayPal Holdings, and $109 million in Zoom Video Communications. Joining the portfolio are multiple Chinese companies including streaming behemoths Bilibili Inc. and iQiyi Inc.

Sea Ltd., a Singaporean group, is also on the list, and is among the best-performing companies in the world in the last 18 months.

Son said Softbank's main objective is to explore different aspects of potential investments, but that their principal focus remains on companies "that drive the information revolution."

Last week, Softbank reported $12 billion profits in the first three months of the year, exceeding projections by more than 70 percent.

Son is putting in more muscle into the group's investment activities – from startups to publicly-listed equities at a time when blue-chip tech stocks are hovering within record highs. Softbank is now homing in on investments valued at over $11 billion in publicly-traded stocks, sources with knowledge of the matter disclosed.

Meanwhile, Son has successfully sparked a turnaround at Vision Fund, whose stakes in office space rental groups Uber Technologies and WeWork had created $11 billion in losses in the previous quarter.