The market listens when Carl Icahn invests in a company and presses for changes. Goldman Sachs said only a handful of activist investors have the power to move stocks the way he does. The Wall Street firm analyzed 2,142 shareholder activism campaigns since 2006 and identified the investors with the most number of campaigns. Then, it looked at the average target return compared to the sector during different periods after a campaign is announced. “A wide performance distribution exists for both successful and unsuccessful activist campaigns and varies by type of activist demand,” Goldman’s head of U.S. equity strategy David Kostin said in a note. Paul Singer’s Elliott Management is the most prolific activist with 53 campaigns launched since 2006. Elliott’s action tends to spark a short-term pop in the targets — a 10 percentage point outperformance against the sector in the three months after the launch. However, the outperformance typically fades as time goes on. Elliott was one of the five activist investors that targeted Salesforce this year. This campaign against Salesforce ended after the board elected a director from ValueAct . The stocks Carl Icahn invests in tend to enjoy a double-digit boost in the 12 months after he starts an attack, according to Goldman. Icahn is currently in a brewing proxy fight with biotech company Illumina . Other activists that have a similar impact on stocks during the time frame are Ancora Advisors and Clinton Group, Goldman said. Shareholder activism could continue its momentum this year with a challenging macro environment, Kostin said. There was a total of 148 campaigns against 120 distinct U.S. corporations during 2022, a roughly 20% jump compared to 2021, ranking among the top five most active years since 2006, Goldman said.