(Reuters) -Shares of OpenDoor Technologies Inc, a home-selling platform backed by SoftBank Group, surged at the start of trading in their Nasdaq debut on Monday only to reverse course and fall almost 11% in a weak broader market. The stock recouped some losses and was last trading down 2.1% at 13:02 ET. The company, formed by a merger with venture investor Chamath Palihapitiya’s Social Capital Hedosophia II, began trading at $31.47, up 6.7% from Social Capital’s last close. OpenDoor said in a filing on Friday it had 544.4 million outstanding shares after the merger, giving it a market capitalization of $17.2 billion at Monday’s opening price. The company, backed by a $400 million investment from SoftBank Group, was hit hard by the pandemic this year, and cut 35% of its workforce in April. As the home resale business started to recover, OpenDoor looked for capital to fuel expansion and opted to go public by merging with Social Capital at a $4.8 billion valuation. The company got about $1 billion cash in the deal, including $600 million from Palihapitiya and other investors including BlackRock and Healthcare of Ontario Pension Plan. Social Capital is a special purpose acquisition company (SPAC) that raised $360 million in its debut in April at $10 per share. SPACs are shell companies that raise money through an initial public offering (IPO) to buy a private company and take it public and have become a popular alternative to traditional IPOs. Another Palihapitiya-backed SPAC took Richard Branson’s space tourism company Virgin Galactic Holdings Inc public last year. Glenn Solomon, a board member at OpenDoor and a managing partner at GGV Capital, one of OpenDoor’s early investors, said the company’s goal had always been to go public due to its reliance on capital.