Little error. Huge impact.

"Are you sure you want to proceed with this transaction?" At least that kind of question I would have expected in yesterday's Mizuho disaster. To recap, a broker at Tokyo-based Mizuho Bank accidentally sold 610.000 J-Com stocks for 1 Yen, instead of selling 1 J-Com stock for 610.000 Yen. Tiny difference.

As an analyst looking after data quality, it seems odd that the system would even allow such a stupid transaction. As a general rule, I would have expected that the selling price is checked against last close, last sale, or some average. Apparently, this was not the case, and the system relied on the user (duh!) to do the quality check.

Maybe the expected loss of 30 Billion Yen (approx. 210 Million Euro) helps, getting some data quality program in place. As I keep telling clients: "you gotta check data quality as much upstream as possible, ideally when it gets entered, generated, submitted, loaded or otherwise activated."