A mysterious Twitter user is attracting a swarm of Japanese traders

The Okasanman account scavenges through a huge range of sources, at all hours, to find potentially market-moving news

On a day when billions in profits and losses would be determined by split-second trades, the salaried professionals of Japan’s financial markets were glued to their news terminals. Another group was staring at the feed of an anonymous Twitter account.

It was shortly after noon on Jan. 29, 2016, and people with money at stake were waiting for the Bank of Japan to announce its monetary policy. While the decision’s date is set in advance, nobody knows its timing.

“It’s a negative interest rate bazooka!” wrote the Twitter user who goes by the handle Okasanman, attaching a screenshot of an