As the most closely watched insider-trading trial in a generation wraps up, it has become increasingly clear that Raj Rajaratnam, the billionaire hedge fund mogul at its center, has no reason to smile.

The 53-year-old’s well-paid defense team came out fists pumping when they started their case last week, saying they would show that the prosecution “didn’t do their homework” because the alleged illegal tips were either already widely known or they didn’t matter to Rajaratnam, who traded for other reasons.

But as Rajaratnam’s final witness, Gregg Jarrell, finishes up today, the defense’s claims appear insubstantial in contrast to the mountains of evidence provided by the government — including 45 wiretaps and three cooperating witnesses who say they shared those illegal tips with Rajaratnam.

Worse yet, even the colorful charts and graphs from Jarrell, intended to show the tips weren’t material, often served to do the opposite.

For example, on allegations that Rajaratnam traded ahead of Goldman Sachs’ first quarterly loss as a public company in late 2008, the University of Rochester economics professor’s charts show the first news story on Goldman’s earnings woes emerged a week after Rajaratnam sold his Goldman stock on Oct. 24.

Goldman CEO Lloyd Blankfein testified that the earnings numbers, provided to the board on Oct. 23, should not have been shared.

The jury also heard Rajaratnam, on a wiretap, bragging about the tip to an employee.

Other defense missteps regarding stock trades and publicly available information include:

* Advanced Micro Devices’ acquisition of ATI in 2006. First news of the merger was in May, but Rajaratnam’s tip was in March, Anil Kumar has testified.

* Integrated Circuit Systems selling itself in 2005. Jarrell’s charts show no “chatter” on the merger before it happens, but wiretaps show Rajaratnam saying “will you buy me some” on the tip from Adam Smith, five months before a deal was announced.

The defense also suffered a huge blow when it emerged that Rajaratnam wired $15 million to the hedge fund of his star witness, Rick Shutte, weeks before the trial started.

Last week the hedge fund billionaire indicated he was happy with the defense’s case. “I can’t comment, but you can see me smiling,” he said when asked how the trial was going.