WASHINGTON -- Blistered by lawmakers for "unbridled greed," Goldman Sachs executives on Tuesday unflinchingly defended their conduct and denied that the huge Wall Street investment bank helped cause the near-meltdown of the nation's financial system.

While the famous firm fights for its reputation, senators said the company's behavior leading up to the financial crisis clearly demonstrated a need for stronger regulation.

Legislation would crack down on the kind of lightly regulated housing market investments that helped set off the crisis in 2007.

Through hours of testimony to a Senate investigative subcommittee, present and former Goldman officials disputed, sometimes testily, the Securities and Exchange Commission's recent fraud allegations against the company.

They strongly denied that the firm cashed in on the housing crash by crafting a strategy to bet against home loan securities while misleading its own investors.

"I will defend myself in court against this false claim," said Fabrice Tourre, a 31-year-old Goldman trader who, along with the firm, was charged with civil fraud by the SEC.

"I deny, categorically, the SEC's allegation."

Senators from both parties verbally pounded the Goldman executives, accusing them of financial gambling that helped nearly derail the entire U.S. economy.

"As we speak, lobbyists fill the halls of Congress, hoping to weaken or kill legislation aimed at reforming these abuses," said Sen. Carl Levin, D-Mich., the panel's chairman. "Wall Street is on the wrong side of this fight."

Levin accused Wall Street firms of selling securities they wouldn't invest in themselves. That's "unbridled greed in the absence of the cop on the beat to control it," he said.

At least in Las Vegas, said Sen. John Ensign, R-Nev., "people know the odds are against them. They play anyway. On Wall Street, they manipulate the odds while you're playing the game."

The SEC said Tourre marketed securities without telling buyers that they had been chosen with help from a Goldman hedge fund client who was betting that the investments would fail. The commission alleged that Tourre told investors the hedge fund, Paulson & Co., actually bought into the investments.

Tourre said he didn't recall telling investors that.

Hour after hour, the executives stood their ground, rejecting accusations that Goldman helped fuel the financial crisis that plunged the country into recession, only acknowledging bad business judgments.

"We did not cause the financial crisis. ... I do not think that we did anything wrong," said Michael Swenson, who runs Goldman's structured products group trading.

Tourre said: "I am saddened and humbled by what happened in the market in 2007 and 2008. ... But I believe my conduct was proper."

At times, the senators and the hearing's witnesses, who have long marketed complex mortgage investments like collateralized debt obligations, seemed to struggle to explain themselves to the other side.

The senators cast Goldman's efforts to bet against securities as a contributor to the crisis. Goldman officials described their use of such trading tools as a way to reduce risks for the company and its clients.

In a January 2007 e-mail, Tourre had called himself "The fabulous Fab ... standing in the middle of all these complex ... exotic trades" that he had created "without necessarily understanding all of the implications of those monstrosities!!!"

Tourre told the panel: "I regret the e-mails. They reflect very bad on the firm and myself. I wish I hadn't sent them."

At one point, about a half dozen protesters entered the committee room, dressed in prison stripes with names on signs around their necks of Tourre and Goldman CEO Lloyd Blankfein, who was scheduled to testify late in the day.

"Fabulous Fab is not so fab when he takes from the poor," the protesters spoke as a chorus before the hearing started. "We want to see these guys behind bars." They quietly hissed at times during the testimony.

When the first panel of Goldman officials got up to leave, one of the protesters ran toward them and shouted, "You have no ethics, Fab."

The protesters later were taken out of the room by a Capitol Police officer.

Sen. John McCain, R-Ariz., said that while there may not be proof that Goldman did anything illegal, a reading of e-mails from Goldman officials bragging about profiting from bets against the housing market showed "there's no doubt their behavior was unethical and the people will render a judgment, as well as courts."