The witness, Louis Martin "Marty" Blazer III, signed a plea agreement last week admitting guilt to five federal criminal charges.
A former UBS trader suspected of manipulating precious metals prices has been arrested.
A former Bank of America technology consultant allegedly shared more than 50 trading tips with friends, according to U.S. government documents.
Shkreli's lawyer said the $3 million would be used to pay tax and legal expenses, and that he is not a flight risk.
The notorious pharma bro Shkreli denies claims he looted a drug company he founded to pay off hedge fund investors he allegedly defrauded.
The pharma bro Shkreli previously won permission to speak at two other universities, but neither event happened because of protests.
Jack Vitayanon, 41, allegedly had been distributing meth for several years and was seen on a video chat smoking the drug in his residence.
Shkreli, who is accused of securities fraud, is free on $5 million bail, and normally must stay in New York.