The CEO of the world's largest money management firm wrote a letter to a thousand CEOs, cautioning them that making profits is no longer enough - they must also have a positive impact on society.

"Society is demanding that companies, both public and private, serve a social purpose," wrote Lawrence Fink, chief of BlackRock Management.  His company manages US$6.3 Trillion (with a T and an R) in assets.  His annual letter to the globe's top CEOs added that companies needed to demonstrate a strategy for long-term value creation and financial performance, and that understanding a company's effect on the world was a key component.

"To prosper over time, every company must not only deliver financial performance, but also show how it makes a positive contribution to society.  Companies must benefit all of their stakeholders, including shareholders, employees, customers, and the communities in which they operate," Fink wrote.  "Without a sense of purpose, no company, either public or private, can achieve its full potential."

So-called "impact investments" designed to improve the world are becoming more popular, as more companies consider how their actions affect society as well as their bottom line.  But the message isn't going to go over well with corporate leaders who believe that their sole obligation is to rake up profits or maximize returns to shareholders.