Wells Fargo & Co , the fourth-largest U.S. bank, reported a 21 percent increase in fourth-quarter profit, helped by double-digit revenue growth in multiple business units and lower credit costs.

The San Francisco-based bank said earnings rose to $3.4 billion, or 61 cents a share, from $2.8 billion, or 8 cents a share, a year earlier.

Analysts on average expected a profit of 61 cents a share, according to Thomson Reuters I/B/E/S.

Revenue increased 12 percent to $21.5 billion.

Shares of Wells Fargo were down 1.6 percent at $31.97 in trading before the market opened.

(Reporting by Joe Rauch; Editing by Lisa Von Ahn)