Shares of energy giant Chevron Corp. tumbled Friday after losses from refining operations cut fourth-quarter profit to less than analysts expected.

The second-largest U.S. energy company earned $5.1 billion, or $2.58 a share, in the last three months of 2011, compared with $5.3 billion, or $2.64 a share, in the year-earlier period.

Analysts were expecting per-share earnings of $2.84.  

Shares fell $3.11, or 2.9 percent, to $103.47 in late morning trading.

Revenue in the fourth quarter was $58 billion, up from $52 billion in the fourth quarter of 2011, a gain the San Ramon, Calif.-based company attributed to higher prices for crude oil and refined products.   

Refining and marketing operations in the fourth-quarter swung to a loss of $61 million, which offset an 18 percent increase in exploration and production to $5.74 billion during the last three months of 2011.

Net liquids production was 1.81 million barrels a day in the fourth quarter, down from 1.94 million barrels a day in the year-ago period. Net oil-equivalent production was 2.64 million barrels a day, down from 2.79 million barrels a day in the year ago period.  

For all of 2011, Chevron earned $26.9 billion, or $13.44 a share, up 41 percent from $19 billion, or $9.48 a share in 2010. Annual revenue was up 23.3 percent to $253.7 billion.