The Chinese state-owned utility has agreed to buy Australian power assets believed to be worth almost $4 billion.
No reason has yet been given for Tony O'Malley's "mutually agreed" stepping down.
Virginia Nemeth had sought to invalidate a deal for 25 percent of her divorce settlement on the grounds that she was "irrational" when she signed it.
The U.S. litigation firm announced Thursday it will open a Sydney office next month with two partners recruited from Herbert Smith Freehills and one relocated from Los Angeles.
The ASX-listed plaintiff's firm has already inked deals to acquire three British law practices for $36 million.
The listing of Mighty River Power is expected to be New Zealand's largest-ever IPO.
A significant amount of yen is flowing into Southeast Asia as Japanese companies seek growth outside the country. The lawyers aren't far behind.