Sobig.F became one of the most widespread viruses ever , crippling corporate e-mail networks and filling home users ' inboxes with a glut of messages .
Since surfacing late Monday , Sobig.F has been crippling corporate e-mail networks and filling home users ' inboxes with a glut of messages .
The yield on the 3 5 / 8 percent February 2013 note dropped 2 basis points to 3.66 percent .