According to one embodiment, a securities trading system comprises a plurality of order sharing devices and a plurality of ordering devices. The order sharing device sends each telegram to the ordering device of a master system and the order sharing device of a slave system. The order sharing device sends each of the telegrams to the ordering device of the slave system to switch from the slave system to the master system when a failure is detected in the ordering device of the master system. The ordering device calculates statistics from market information, and uses the statistics to judge whether to permit the placement of an order with the stock exchange apparatus in the case of the master system.