With all the talk about the impact of activist investors, there appears to be some evidence that their actions do, in fact, benefit shareholders.

Bloomberg performed a five-year return analysis of companies that have been subject to actions urged on them by activist investors, reporters wrote in a story titled “Raiders-Turned-Activists Prove Boon for Stocks Beating S&P 500.”

Shares of those 81 companies enjoyed an average gain of 48 percent over the last five calendar years—a return that topped the Standard & Poor’s 500 Index by 17 percentage points over the same period, according to Bloomberg.

The analysis involved an examination of data related to activists’ targets beginning in January 2009, and measured the change in share price between the day before the activists’ investments were made public though December 31, 2013. Only large companies with market capitalizations of at least $1 billion were considered.

One academic who has performed a similar analysis agreed with Bloomberg’s findings.

“Some people argue that the activist hedge funds benefit at the expense of the other shareholders, but that doesn’t happen,” Columbia Business School professor Wei Jiang told the news service. “It’s not like they pump and dump and the rest of the shareholders suffer.”

According to Bloomberg, the companies where shareholders benefited amid activist activity over the past five years include McGraw-Hill, where Jana Partners pushed for reorganization; Office Depot, which was targeted by Starboard Value LP; Yahoo!, where Daniel Loeb’s Third Point pushed for change; and Illinois Tool Works, targeted by Ralph Whitworth’s Relational Investors.

Some of those activist investors are on Martin Lipton’s good list, while others are not, according to the Wachtell, Lipton partner’s recent criticism of the group.

Should Bloomberg perform similar analyses in the future, its reporters will have even more information to assess. Last year, the news service notes, 369 companies were targeted by activist investors—a 12 percent increase over 2012, according to data from Hedge Fund Solutions. “The increase,” Bloomberg reports, “was fueled by an almost tripling of money flowing to the activist hedge funds over the past five years, to $93 billion at the end of 2013.”