Fund manager Raj Rajaratnam made $1 million in two minutes of frantic calls after receiving an inside tip about a big investment in Goldman Sachs Group Inc at the height of the financial crisis, prosecutors said at the Galleon founder's insider trading trial.

In the biggest Wall Street insider trading case since the 1980s, U.S. prosecutors have persistently pressed phone tap evidence that Rajaratnam had a direct line to his friend and then Goldman Sachs director, Rajat Gupta, who leaked bank secrets to him. The trial is in its fourth week and could last until the end of April.

On Wednesday, the Manhattan federal court jury heard another FBI phone tap to support government allegations Rajaratnam knew a day before it was announced in September 2008 that Goldman would receive a $5 billion investment from Warren Buffett's Berkshire Hathaway Inc.

In the phone tap of a call on September 24, 2008, between Rajaratnam and his personal Galleon trader, Ian Horowitz, he is heard describing his efforts the previous day to buy shares two minutes before the 4 p.m. stock market close.

I got a call at 3:58, right? Rajaratnam said, referring to the September 23 conversation with Gupta about a Goldman board meeting that day. Saying something good might happen to Goldman, right?

But when he then called Galleon, the first trader he reached was unable to complete it.

I, so I told Ananth to buy some, he was fucking around, he can't, you know. So I went to Gary and just buy me, right?

The full name of trader Ananth was not known and the other person was Gary Rosenbach, then a Galleon manager.

Prosecutors said Rajaratnam ordered $43 million worth of Goldman stock, $27 million of which was filled in two minutes. Rajaratnam's profit was $1 million, the government said. Gupta, who has been charged by U.S. market regulators in the case, is also a former global managing director of the elite McKinsey & Co consultancy.

Defense lawyers argue that Sri Lankan-born Rajaratnam, 53, purchased stocks on September 23, 2008, in anticipation of the government bailing out banks, which would have been good news for the whole financial industry.

In all, Rajaratnam is accused of making $45 million in illicit profits from 2003 to March 2009 on dozens of stocks based on tips from high-placed corporate insiders. His defense is that he made money based on analysis and public information. Galleon hedge fund managed $7 billion at its peak. It was wound down in late 2009 without losses to investors.

The audio tape was played during the testimony of Adam Smith, a former Galleon portfolio manager who pleaded guilty to securities fraud and conspiracy in January and agreed to testify against his old boss. He is among 19 out of 26 people charged in the sprawling case to have pleaded guilty.

Under cross-examination, Smith acknowledged he had lied to Galleon about losing one of the firm's computer laptops after Rajaratnam's October 2009 arrest, and had actually thrown it away in a rural part of upstate New York, where he lives.

Smith, 39, also acknowledged pressure from prosecutors and the FBI, including wiretaps last year after he left Galleon.

He was asked by defense lawyer Terence Lynam whether he was willing to do whatever the FBI and prosecutors told him to do to help himself, including avoiding obstruction of justice charges and receiving a lighter prison sentence. Smith had agreed to be recorded in a call with trader Horowitz.

It was an absolutely impossible situation for me but I did choose to do it. It was impossible because anything I chose would be a bad outcome for me ... The FBI put pressure on me to do it, they said they had evidence against Mr. Horowitz, said Smith, whose testimony began on Tuesday.

One lighter note came when Assistant U.S. Attorney Andrew Michaelson misinterpreted a pm reference in his notes, meant to indicate that Smith had been a portfolio manager.

When you were, uh, prime minister, Michaelson began, prompting much laughter in the courtroom.

Not yet, Smith countered.

The case is USA v Raj Rajaratnam et al, U.S. District Court for the Southern District of New York, No. 09-01184.

(Additional reporting by Jonathan Stempel; Editing by Gary Hill)