UPDATE: Der Spiegel says @Russian_Market is being investigated by Bundesbank
From Der Spiegel:
According to research by the Bundesbank, the rumors about the alleged Weidmann's resignation apparently first appeared in the Twitter accountrussian_market on - an aggregator of financial news at least nearly 37,000 followers.
There's always been an abundance of rumors in the world of finance, but after Twitter it became very easy to spread just about anything.
Today was a day filled with rumors on all sorts of things, and after the Dax started selling off, much talk started. Most notably, was a rumor that the president of the Bundesbank, Jens Weidmann, had resigned.
Bundesbank did not like this one big, first calling it "utter garbage" - yes that is the actual quote. Later they said that they worried the rumor was an attempt to manipulate the market.
Like all rumors, it is really difficult to know where it started, but the first post on Twitter was this one:
And a screenshot in case it gets deleted: