If a friend is arrested for manipulating the securities and futures market, first of all, it is necessary to find out which public security organ arrested him and inform his family, because according to the law of our country, after a criminal suspect is arrested, only his close relatives have the right to handle affairs, but not his friends. Secondly, ask the public security organs for information. If the circumstances are minor, you may apply for changing compulsory measures. If the circumstances are serious, it is recommended to hire a lawyer to help. Criminal Procedure Law: Article 33 A criminal suspect has the right to entrust a defender from the day when he is interrogated for the first time by the investigation organ or compulsory measures are taken. During the investigation, only lawyers can be entrusted as defenders. The defendant has the right to entrust a defender at any time. When interrogating a criminal suspect for the first time or taking compulsory measures against him, the investigation organ shall inform him that he has the right to entrust a defender. The people's procuratorate shall, within three days from the date of receiving the case materials transferred for examination and prosecution, inform the criminal suspect that he has the right to entrust a defender. The people's court shall, within three days from the date of accepting the case, inform the defendant of the right to entrust a defender. If a criminal suspect or defendant requests to entrust a defender while in custody, the people's court, the people's procuratorate and the public security organ shall promptly convey it. If a criminal suspect or defendant is in custody, his guardian or near relative may also entrust a defender. After accepting the entrustment of a criminal suspect or defendant, the defender shall promptly inform the case-handling organ.