FX renews 'Sons of Anarchy' for fourth season

FX has picked up "Sons of Anarchy" for a fourth season.

The network has placed a 13-episode order for the show to return next year.

"Sons" has been averaging 4.9 million viewers on a first-run basis, 8.6 million when you fold in repeats. It ranks as the highest-rated series ever for FX.