Activist investing is typically practiced by long-only hedge funds. They use their "ownership" in the company as justification for calling for improvements that will increase shareholder value. Although companies can respond by trying to paint such investors as "short-termists," it's hard to disparage a fellow owner of the company. Activists will typically encourage the company to take actions meant to benefit all stock holders (including management). With his Lehman investment, Einhorn might have created a template for a new type of activist investor: the activist shorter. Einhorn made his case for why Lehman would drop through a series of speeches and media appearances. With a good argument and his own track record as credibility, people listened. Shorts are unfairly vilified in the press for not being true owners and for wanting to drive down the stock. Yet, as Einhorn and another prominent shorter, RealMoney.com contributor Doug Kass, have pointed out: Are management, stock analysts or stockholders of a company who talk up a stock not guilty of the same bias that a short has when talking down a stock? All long and short holders of stock deserve to make money if they can articulate a point of view before the fact and see it borne out. Einhorn simply had a better argument than Callan and the market sided with him. Lehman's stock dropped 16% between the time when Einhorn first made his public remarks on the bank's problems on May 22 and last Friday.