The lender has been slapped with a penalty of SFr 2m (£1.6m) by the Swiss stock exchange (Six) for sitting on information relating to a strategic change to scale back its investment banking operations.
UBS was aware of the information on 29 October 2012 and failed to inform the market until the morning of 30 October 2012. Regulators said the delay was in breach of rules that stipulate firms should have ensured an announcement was made on the same day it became aware of the information.
"The company was not authorised to postpone the announcement while awaiting the decision of its board of directors, i.e. until the morning of 30 October 2012, because a potentially price-sensitive fact already existed prior to the board's decision and the conditions for a postponement of disclosure were no longer given," Six said.
Although specific requirements vary between regulators, many authorities dictate listed entities must reveal market sensitive information as soon as they become aware of it, no matter of whether markets are open or not.
UBS responded to the ruling by stating it disagreed that it should have made the disclosure earlier.
It told Reuters: "UBS continues to believe that it was and is appropriate to issue an ad hoc announcement only after a final approval of the strategy by the Board of Directors."