Elon Musk has become the first person to top US$700 billion in net worth after Delaware’s Supreme Court revived a massive Tesla stock-options award that had been cancelled last year, according to the Forbes billionaires index.

Twitter sued Elon Musk on Tuesday for violating the $44 billion deal to buy the social media platform and asked a Delaware court to order the world's richest person to complete the merger at the agreed $54.20 per Twitter share, according to a court filing.