It's probably not the way GlaxoSmithKline (GSK) had hoped to start the second half of the year. The U.S. unit of GSK today agreed to plead guilty and pay a criminal fine of $956.8 million for marketing drugs for unapproved uses.

The London-based pharmaceutical giant admits in a charging document that it didn't report safety data of its Avandia diabetes drug to regulators, unlawfully marketed Wellbutrin for weight loss and other purposes for which it wasn't approved by U.S. regulators and illegally promoted Paxil for adolescents and children.

Last November, GSK agreed to pay the U.S. government $3 billion to settle several criminal and civil probes related to its sales and marketing practices. The agreement, which resolved prolonged investigations of whether the company illegally marketed some of its top-selling drugs and defrauded Medicaid, will be the largest pharmaceutical marketing settlement in U.S. history when finalized.

The settlement “is a significant step toward resolving difficult, long-standing matters which do not reflect the company that we are today,” GSK CEO Andrew Witty said in a statement last year. “In recent years, we have fundamentally changed our procedures for compliance, marketing and selling in the U.S. to ensure that we operate with high standards of integrity and that we conduct our business openly and transparently.”

GSK also has spent more than $700 million to resolve patient lawsuits claiming Avandia caused heart attacks and strokes. Settlements in those cases averaged about $50,000 each.

For more on the recent criminal fine, read Bloomberg.

And for more on Glaxo from InsideCounsel, read:

Glaxo has right to sell generic Paxil

Glaxo agrees to pay $3 billion to settle marketing probes

Former Glaxo lawyer indicted again over drug probe

Glaxo GC Accused of Obstructing Investigation

Glaxo Said to Pay More Than $250 Million to Settle Avandia Death Lawsuits