(Corrects say $90 million from Motive Partners is an "offer to backstop" and not an "investment" in paragraph 3)

Sept 13 (Reuters) - Forge Global Inc, a marketplace that allows people to trade in shares of private companies, will go public through a merger with a blank-check firm valuing the combined company at $2 billion.

The deal with Motive Capital Corp, announced on Monday, includes $68.5 million in funding from ION Group, Singapore state investor Temasek and Adit Ventures in the form of private investment in public equity, or PIPE.

Certain funds managed by Motive Partners, a private equity firm that sponsors Motive Capital Corp through its affiliates, have also offered to provide up to an additional $90 million as a backstop for the deal, in case the SPAC's investors choose to redeem their shares.

Forge's marketplace has nearly 400,000 users, and shares of more than 400 private companies have traded on its platform since inception for a total volume of over $10 billion.

Private market investments have in recent months become attractive options for investors looking out for sources of higher yields in a near-zero interest rate environment.

The merger is expected to provide gross proceeds of about $532.5 million to the combined company, which would be lead by Forge Chief Executive Officer Kelly Rodriques.

The deal is expected to close in the fourth quarter of this year or the first quarter of 2022.

SPACs like Motive Capital Corp are publicly listed investment vehicles that have no operations and are raised with the purpose of finding a private company to merge with at a later date, to take it public by sidestepping a traditional IPO. (Reporting by Sohini Podder in Bengaluru; Editing by Aditya Soni)