The Supreme Court threw out an antitrust lawsuit against ten leading investment banks, finding that such suits are “clearly incompatible” with current U.S. securities laws. In the majority decision written by Justice Stephen Breyer, the Court said that allowing antitrust action in securities lawsuits presents “substantial risk of injury to the securities markets” and a high likelihood that courts below would apply inconsistent standards.

In the 1990s, the banks named in the suit formed syndicates and acted as underwriters for hundreds of tech companies' IPOs, gauging investor interest in the companies and marketing them. Sixty investors filed a class-action suit in 2002 after losing money when several of those tech companies' stock values plummeted.

In Credit Suisse Securities et al. v. Billing et al., plaintiffs alleged the banks, as underwriters, inflated share prices and violated antitrust laws by conspiring to impose harmful conditions upon investors, including making “laddering” and “tying” arrangements and taking excessive commissions. The Court found the conduct in question is “central to the proper functioning of well-regulated capital markets” and “essential to the successful marketing of an IPO.”

The Court added that complex technical nature of securities law means the SEC holds the expertise to determine the fine line between what is and is not forbidden practice. “There is a serious risk,” Breyer wrote, “that antitrust courts, with different nonexpert judges and different nonexpert juries, will produce inconsistent results.”