SoftBank Group (SFTBY) is urging WeWork to postpone its plans to go public, multiple media reports indicated Tuesday, amid concerns over its weaken valuation complex corporate structure.

WeWork, the office space leasing group co-founded by We Companies owner Adam Neumann, was thought to be preparing to pitch investors later this week for an IPO that would raise between $3 and $4 billion while valuing the New York-based start up in the region of $20 billion.

However, the Financial Times reported Tuesday that SoftBank, WeWork's top shareholder, wants to shelve the listing lest is Vision Fund, whose last investment valued WeWork at $47 billion, is forced to write-down more than half of its stake. Bloomberg also reported that Japan-based SoftBank is concerned with WeWork's complicated corporate set-up, as well as its three-class voting structure.

SoftBank's reported concern is just the latest in a series of negative headlines linked to WeWork's planned IPO, which at one stage valued the start-up at more than $65 billion. Securities and Exchange Commission filings for the listing revealed $3 billion in losses for the group over the past three years as well as a $17 billion financial commitment to future office leasing at a time when both the U.S. and global economies are slowing towards potential recession.

SoftBank is estimated to have plowed a substantial chunk of its $100 billion-plus Vision Fund -- just under $11 billion -- into WeWork, and would lose money from the investment if the IPO is priced anywhere under $25 billion. 

Originally founded in 2010, New York-based WeWork takes out leases on commercial property and then carves up the space and rents it to businesses, who it refers to as "members," in return for providing various services as a management company, including installing telecommunications and various amenities, and managing the properties.

The IPO prospectus, filed in mid-August, shows that total expenses, including WeWork's cost to manage properties and its general corporate costs, led to an operating loss of $1.37 billion in the first six months of this year, or 89% of its total revenue. That is up slightly from the same period of last year, even though revenue doubled in that period to $1.54 billion.

-- TheStreet's Tiernan Ray contributed to this report.