By Christine Harper April 30 (Bloomberg) — Lloyd Blankfein , chief executive officer of Goldman Sachs Group Inc. , said that a “callousness” toward clients demonstrated in some e-mails released to the public this week is unacceptable and doesn’t represent the firm. “There were some e-mails where some people were projecting I would say, at best indifference, and at worst a callousness,” Blankfein, 55, said in an interview on the “ Charlie Rose ” television show airing tonight, according to a transcript. While he said those e-mails aren’t representative of the firm as a whole “it’s inexcusable if 10 people think that way or thought that way.” Goldman Sachs, the Wall Street firm that generates more trading revenue than any other, faces a U.S. Securities and Exchange Commission civil-fraud lawsuit over its sale of a mortgage-linked security. It is under criminal investigation by federal prosecutors, said two people familiar with the matter. Blankfein, who has run the company since June 2006, defended the firm’s actions this week under interrogation from a U.S. Senate subcommittee, which released 901 pages of documents including e-mail that showed employees disparaging securities they were offering to clients. Most of the complex derivatives the firm concocted and traded had a social utility, he said, while others may have gone too far. “If the issuants themselves are too complicated, become too illiquid as it turns out that they were, notwithstanding the purpose you may say, ‘Let’s not do those things,’” he said, according to the transcript. “So in hindsight I wish we had not done some of those things.” Stock Decline The stock fell 9.4 percent today to $145.20, in New York trading, its biggest drop since the SEC brought the suit on April 16. The company has slid 21 percent since the case was filed, losing $21 billion in market value. Goldman Sachs must improve communication with the public, Blankfein said, a role he said he finds especially difficult. “That’s a huge challenge, I would just say it’s my deficiency,” he said. “We can’t exist in the current state that we’re in and we understand that,” he said. “So we have a lot of work to do.” Blankfein defended the role that Goldman Sachs , and Wall Street as a whole, plays in making markets. “You could call it a casino, but if it is, it’s a very socially important casino,” he said. Goldman Sachs, which reported record earnings last year even as it repaid $10 billion of taxpayer bailout funds, inadvertently helped cause the worst financial crisis since the Great Depression, Blankfein said in an interview with National Public Radio yesterday. “Some of the things that Goldman Sachs did contributed to the crisis,” Blankfein told NPR, according to a transcript of that interview. “So, for example, Goldman Sachs did transactions for companies that involved lending them a lot of money, maybe too much money. We financed real estate that was probably overleveraged.” To contact the reporter on this story: Christine Harper in New York at charper@bloomberg.net