The U.S. Supreme Court took the unusual step Friday of dismissing an appeal from Facebook in a securities case after having already heard oral arguments, explaining only that the case had been "improvidently granted."

The justices had agreed in June to take up Facebook's appeal to defeat a securities class action brought by investors over two 2018 stock drops that wiped out more than $200 billion from the company's market capitalization. One of those occurred following media reports about misuse of user Facebook data by the political consulting firm Cambridge Analytica.