Withdrawal of registration by a broker-dealer, agent, investment adviser, or investment adviser representative becomes effective 60 days after filing of the application to withdraw or within such shorter period as required by rule or order under this chapter unless a revocation or suspension proceeding is pending when the application is filed. If a proceeding is pending, withdrawal becomes effective when and upon such conditions as required by rule or order under this chapter. The Administrator may institute a revocation or suspension proceeding under section 642 within one year after the withdrawal became effective automatically and issue a revocation or suspension order as of the last date on which registration was effective if a proceeding is not pending.