For his son’s bar mitzvah in 2008, hedge fund manager Murray Huberfeld chartered a JetBlue plane and invited hundreds to an oceanfront party in Palm Beach, Florida. An Orthodox pop star known as the “Jewish Elvis” entertained the guests, who Huberfeld says included investors in his fund.

Intimate ties and fundraising inside a close-knit world of observant Jewish businesspeople in New York, Florida and Israel are central to the $1.25 billion hedge fund firm Huberfeld has helped lead, Platinum Partners. Now those ties are being tested as two sets of federal prosecutors as well as securities regulators delve into Platinum's operations.