Swiss bank UBS may have lost as much as 350 million dollars (£227 million) because of technical glitches on the US Nasdaq stock exchange the day Facebook went public, according to reports.
CNBC and The Wall Street Journal, citing people familiar with the matter, reported that UBS was considering legal action against Nasdaq.
UBS spokeswoman Karina Byrne confirmed that the bank lost money due to Nasdaq's technical issues when the social networking company's stock began trading on May 18.
Ms Byrne declined to disclose the amount but said it was "not material" to the bank. She said UBS had not taken legal action but was considering its options for recovering its losses.
"Given the size of our US equities business and our role as a major market maker, UBS was affected by these issues, as we believe other market participants may have been," she said in a statement.
Nasdaq declined to comment on the reports.
The £227 million figure dwarfs previous estimates for the combined losses resulting from technical glitches at Nasdaq during Facebook's first day of trading. This week, the exchange said it would hand out 40 million dollars (£26 million) in cash and credit to reimburse investment firms.
Facebook's initial public stock offering was one of the most widely-anticipated market debuts in years. But it quickly turned chaotic. The opening was delayed by half an hour, then technical problems kept many investors from buying shares in the morning, or selling them later in the day, or even knowing whether their orders went through. Some investors complained they were left holding shares they did not want.
According to CNBC and the Journal, UBS placed an order for one million shares but did not receive confirmations and repeated the order several times, so it ended up with much more stock than it intended.
Facebook's stock originally priced at 38 dollars and closed that first day at 38.23, disappointing those hoping for a first-day surge. Nasdaq has said it was embarrassed by the glitches but they did not contribute to the underwhelming returns.