Ting Li and Jan van Dalen of RSM have analysed over a million Twitter messages that mentioned stocks listed on the S&P 100 share index. The researchers then developed an algorithm that looked at the sentiment of the tweets and extracted distinct ‘buy’, ‘hold’ and ‘sell’ signals embedded in them - before comparing them to actual price fluctuations on the stocks over the following days. Li says this could be useful for investors: “This study shows the potential value of information on Twitter for making informed trading decisions."