Wall Street’s Facebook losses keep growing

UBS may have gambled more than $1 billion on Facebook’s IPO.

Fortune — Last week, Morgan Stanley’s CEO James Gorman called those who had bought shares in Facebook’s IPO expecting it to pop “naive.” But it now appears it wasn’t just individual investors who gambled on the social network’s shares and lost. Wall Street was all-in as well.

Late Friday, Swiss bank UBS confirmed that it, too, had lost money trading Facebook’s shares in the days after the company’s IPO. The bank wouldn’t say how much. But theWall Street Journal and CNBC put the loss at $350 million, making it the largest Facebook loser so far by far. Originally, Wall Street’s Facebook trading loss was estimated to be around $100 million. But in the past week or so, some were putting it at double that. Add in UBS’s previous unknown losses and Wall Street’s Facebook hit could be more than half a billion.

MORE: Who really won in Facebook’s IPO mess

UBS is a markert maker, and like other brokers was trying to help its clients get Facebook’s stock. But it’s hard to believe that UBS could lose this much money just buying and selling the stock for others. The company said it tried to sell the Facebook shares it had bought at $35, but ended up exiting some of its shares at below $30.