Twitter is being investigated by the Federal Trade Commission for alleged privacy violations, another setback for a company that has struggled in recent years to protect private user data and account security. The FTC is probing the company for using phone numbers uploaded for security purposes to target people with advertising — a potential violation of a 2011 consent decree in which Twitter agreed to better protect personal data, the company said Monday in a regulatory filing. The probe may lead to a "probable loss" of $150 million to $250 million, the San Francisco-based company said. "The matter remains unresolved...