You have several options for carrying out these transactions. You can choose to work with online brokers who offer securities accounts or brokers who offer share trading using derivatives such as CFDs or contracts for difference. Another option is to contact traditional banks that offer online brokerage services. You can also explore regulated online trading platforms. Before buying or selling Air France-KLM shares, compare the fees, the platform's features and make sure you comply with the regulations in force. Don't forget to take your risk tolerance into account and, if necessary, seek the advice of a financial adviser to make an informed decision.