SAN FRANCISCO: Elon Musk's huge Twitter investment took a new twist Tuesday with the filing of a lawsuit alleging that the colorful billionaire illegally delayed disclosing his stake in the social media company so he could buy more shares at lower prices.

The complaint in New York federal court accuses Musk of violating a regulatory deadline to reveal he had accumulated a stake of at least 5 percent. Instead, according to the complaint, Musk didn't disclose his position in Twitter until he'd almost doubled his stake to more than 9 percent. That strategy, the lawsuit alleges, hurt less wealthy investors who sold shares in the San Francisco company in the nearly two weeks before Musk acknowledged holding a major stake.