UBS has racked up losses up to $350m related to botched trading in shares of Facebook during the company's tumultuous market debut, according to people familiar with the situation.

The Swiss bank is weighing its legal options against Nasdaq OMX, whose technology glitches caused widespread chaos in Facebook's May 18 initial public offering, these people said. A decision hasn't been made though, over whether the firm would ultimately sue the exchange, one of these people said.