The Swiss stock exchange is investigating UBS for possible breaches of public disclosure rules.
The BBC reports the investigation will centre around information the bank published while it was contending with billions of dollars of bad loans in 2007 and 2008.
The bank, the biggest in Switzerland, declined to comment on the investigation.
Earlier this year, UBS was accused of helping Americans evade US taxes by opening accounts in Switzerland.
US authorities wanted the bank to hand over the names of thousands of customers with Swiss accounts.
Last month, UBS signed a deal with the United States designed to end the dispute and will now give the US tax authorities the details of 4450 accounts.
In February, UBS admitted to tax fraud in the US and agreed to pay $US780 million as part of a provisional deal to settle charges that it helped thousands of US clients use Swiss bank accounts to evade taxes.
The BBC reports the bank is trying to rebuild its reputation after the tax probe. It has been hit particularly hard by the credit crisis, suffering from big losses in the US sub-prime mortgage market.
The bank reported a loss of 1.4 billion Swiss francs ($US1.36 billion) between April - June, along with significant outflows of cash. It lost 2 billionn Swiss francs in the first three months of the year.