“Get long and get loud,” or “Go short and get shrill.” These tactics of taking a position in a stock, then spreading the word to persuade others to follow along, is as old as the markets themselves.

Yet this year the jawboning of stocks seems to be happening more often, more publicly, and by bigger-name investors. And it’s no wonder: The world appears to be listening, and acting on the utterances of the do-as-I’ve-done big-money crowd.

When pioneering activist investor and hedge-fund manager Carl Icahn Tuesday disclosed a “large” new position in Apple Inc. (AAPL) shares, the stock added $20.2 billion in market value by the close of trading – more than 13-times the reported $1.5 billion stake and the equivalent of $150 million for each of the 135 characters in his tweet.

via Big-Name Investors Get Long, Get Loud and Get Richer | Michael Santoli – Yahoo! Finance.