The Tokyo Stock Exchange attempted to explain the forces behind the stock and convertible bond system failure that stalled bond trading for four hours on November 1, 2005
“We would like to express our deepest regret and offer our most humble apologies for the great inconvenience that we caused investors and all others concerned when trading on the Tokyo Stock Exchange was suspended from 9:00 a.m. to 1:30 p.m. on November 1st last week.”
When the stock / convertible bond trading system (below “trading system”) was activated at 6:30 a.m, an error occurred during the reading of files that stored data relating to trading participants, causing the trading system to stop. When the information read should have been trading participant data but was not, the system detected this aberration and ceased operations.
At that point, TSE and Fujitsu, Ltd. (below “Fujitsu”) – who is responsible for development and support of the trading system – immediately began investigating the cause of the problem, and attempted to restart the system.
After an attempt at system reboot, the malfunction persisted, causing the system to lockup.
During the recent augmentation of the order processing ability of the trading system, a latent bug that had previously existed in a program connected with trading participant data files was discovered. As such, after confirming with TSE, Fujitsu made a correction to the relevant areas on October 9th, and on October 13th the corrected program was loaded as normal into the trading system, but a step was missing.
The instruction was sent from Fujitsu to Tosho Computer Systems Co., Ltd, who was charged with the loading operations. As a result, the structure of the system after normal loading was incorrect, having a combination of both the normal program and the old program, and the system malfunction occurred during the disk compression process on October 31.
The reason the malfunction occurred on November 1st is because during the disk compression process, the system automatically detected the existence (attributes) of the old program, and disconnected with the normal program.