Asked whether he wanted to see SAC Capital forced to shut down, the Iowa Republican responded diplomatically.
"Maybe I should say yes, but I'm not going to say yes because I'm a legislator," he said. "We pass laws. And then what I'm doing in investigating is what you call oversight to see that the other branch of government faithfully executes the laws.
"So, I think at this point I'm going to leave it up to the executive branch, and I'm going to be a critic. I'm going to oversee it. We're going to make sure that they're doing the right thing. But what you're asking me about today is a step in the right direction, and I think I better let the legal process take its course."
(Read more: SEC pins charges on SAC Capital's Cohen)
"Well, I don't think it's just one company," he said. "I think there's been an attitude and bureaucracy, and I wouldn't want to say it's just in this administration – it could've been in other administrations – that somehow you shouldn't touch the so-called big fish on Wall Street."
Grallsey said that there was "evidence" of this the last time he had an opportunity to question Attorney General Eric Holder.
"I said, 'We've been hearing that you don't really want to prosecute in a criminal way big companies or big individuals because it could upset the whole financial system of the United States, and that you have been consulting with certain quote-unquote experts. And do you do this?'" Grassley said.
"And he, very candidly, said, 'Yes, they do. They do have that fear.' Maybe a lot of people have been getting off scot-free that should've been charged previously because of this, so I'm very happy to see what the Justice Department is doing in regard to SAC. And the reason for that is, maybe this is a change of environment.
"But at least they're taking a necessary step if they think that there's wrongdoing."