A Twitter Inc. investor had sued Elon Musk and said that the world’s richest person’s on-again off-again purchase of the social-media platform and his public attacks on the company were designed to manipulate its stock price.Giuseppe Pampena says that Musk “essentially acknowledged that he had been bluffing all along” about backing out of the deal after he agreed last week to go ahead with his purchase of Twitter, at the originally agreed upon price.According to the securities class-action complaint filed on Monday in Federal Court in San Francisco, the flip-flops and Musk’s accusations about Twitter sunk its stock price, hurting investors while all the while improving Musk’s bargaining position.Musk offered to buy Twitter in April for $54.20 per share, or $44 billion, but then announced his was pulling out of the deal three weeks later.Then, “Musk proceeded to make statements, send tweets, and engage in conduct designed to create doubt about the deal and drive Twitter’s stock down substantially in order to create leverage that Musk hoped to use to either back out of the purchase or re-negotiate the buyout price by as much as 25% which, if accomplished, would result in an $11 billion reduction in the buyout consideration,” according to the suit. “Musk’s conduct was fraudulent and illegal.”Musk has previously been sued at various points along the way in the Twitter buyout saga.The law firms, Quinn Emanuel Urquhart & Sullivan LLP, that represent Musk in several legal matters including the Twitter buyout, didn’t immediately respond outside regular business hours to a request for comment.