Elon Musk can't keep $55 billion Tesla pay package, Delaware judge rules

Elon Musk may not keep a Tesla pay package worth more than $55 billion, a Delaware judge ruled on Tuesday, saying that the Tesla CEO and his company failed to prove that the massive payout was fair.

The ruling comes five years after a shareholder lawsuit accused Musk and Tesla's board of directors of breaching their duties to the electric vehicle manufacturer, wasting corporate assets and unjustly enriching the billionaire.

Tesla shares slid 4% in after-hours trading.