An article published on March 23 tells how finance is influenced by fake tweets. 
The results come from a research done by Fabrizio Lillo, Maurizio Tesconi and Stefano Cresci, members of the SoBigData project.

"Just a tweet! A "chirp" to manipulate market information. Especially if, in the world of social networks, to tweet is not a man. But a robot. The proof is provides by a research, carried out within the EU SoBigData project, by a group of Italian scientists. The experts analyzed 9 million tweets, launched on the social network between May and September, in which they discussed shares listed on the main American stock exchanges. The historical series of securities data (30,032 companies) was then crossed with the financial information of Google Finance concerning the companies themselves."
[...continue reading the italian version]