(Reuters) - Shares of Citizens Financial Group Inc (CFG.N), the U.S. unit of Royal Bank of Scotland Group Plc (RBS.L), rose less than 1 percent in their debut, valuing the company at about $12 billion in the biggest U.S. offering by a bank since the financial crisis.
The offering, which raised $3.01 billion for RBS, is the second biggest in the United States this year after Alibaba Group Holding Ltd's (BABA.N) $25 billion IPO last week.
Citizens Financial's IPO was priced at $21.50, below the expected range of $23-$25.
RBS owned 100 percent of Citizens Financial before the offering.
Citizens Financial's shares were at $21.64 shortly after start of trading.
(Reporting by Tanya Agrawal; Editing by Joyjeet Das)