Notwithstanding any other provision of this division, if in his or her opinion the public interest and the protection of investors so require, the commissioner is authorized summarily to suspend all over-the-counter trading in this state by broker-dealers and agents in any security or summarily to suspend all trading on a national securities exchange located in this state in any security (provided, in the case of trading on that exchange, that the security is not listed on any national securities exchange located outside this state on which trading has not been suspended) for a period not exceeding 90 days, and for successive periods of 90 days. No broker-dealer or agent shall effect any transaction (other than an unsolicited brokerage transaction effected on a national securities exchange located outside this
state) in, or induce or attempt to induce the purchase or sale of, any security in this state in which trading is in any manner suspended under this section, except in performance of a contract previously entered into.