The answer might surprise you.

It's Japanese companies.

Softbank.

It has piled money into tech startups.

Uber slack, Alibaba by Dance and Sawyer.

These air just a few of its high profile investments.

With $97 billion in assets, it's Vision Fund is the biggest private pool of money ever raised.

But it is the nearly 11 billion it has sunk into we work.

That has put the Japanese company and its investment fund under scrutiny.

The shared workspace provider has seen its valuation slashed by 70%.

The massive downgrade has raised concerns about whether Softbank Vision Fund wields more dollars than sense.

Softbank was founded by Masayoshi Son in 1981 to distribute computer software.

Today, it has interest in telecommunications, Internet, transportation, finance, media, robotics, venture capital and much more.

This entrepreneurial zeal has made Massa, as he's known, Japan's second richest man.

It took his vision fund just under one year to raise that 97 billion, mostly from sovereign wealth funds.

But that money is not exactly what it seems.

Most venture capital funds are based on equity, but the vision fund works a little differently.

roughly 40 billion putting by investors is in the form of preferred shares that work like debt.

Only Soft Bank has a full equity stake that names The Vision Fund has to find up to 2.8 billion in interest payments each year.

Softbank finds that money by selling stakes for higher price or by listing companies on the public market.

The fund has reported annual returns of 29% for investors based on cos sky high valuations.

The problem is, a few of them are actually profitable.

Those that have tested their evaluations by listing on the stock market haven't lived up to the hype.

Shares and ride hailing group uber and messaging company Slack have both plummeted since going public.

Undeterred, Massa has just unveiled the vision fund, too.

However, this time investors are proving a lot more cautious.

The high risk strategy of betting on untested business models and paying huge dividends on companies that are not yet profitable could be the vision funds undoing that would hit Softbank's bottom line.