Nasdaq has blamed Facebook’s botched debut last month on flawed computers and ‘‘technical errors.’’
Regulators suspect it may be something more. The Securities and Exchange Commission has opened an investigation into the exchange for its role in the initial public offering of Facebook, according to people briefed on the inquiry. Regulators are examining whether Nasdaq failed to properly test its trading systems, which broke down during the IPO, and whether the exchange violated rules when it rewrote computer code to jump-start trading.
The Facebook investigation comes after a broader inquiry into trading breakdowns and other problems at the nation’s largest exchanges, including two previously undisclosed cases involving Nasdaq’s archrival, the New York Stock Exchange, the people said.
The agency’s enforcement unit, which has opened more than a dozen related cases, is examining whether exchanges lack adequate controls and favor select investors.
As investor confidence in the market wanes, the worry is that missteps by the exchanges are contributing to the dissatisfaction. Since the financial crisis, investors have seen their portfolios erode, prompting them to flee stocks.
‘‘If exchanges have technical problems, that slows capital formation and erodes the confidence,’’ said Senator Jack Reed, Democrat of Rhode Island, who held a hearing this week on the initial public offering process.
While none of the exchanges has been accused of any wrongdoing, the crackdown represents a significant shift. Traditionally, the agency has been relatively cozy with the industry, which is increasingly under pressure to produce profits since the exchanges became publicly traded companies.
“Cases against exchanges are few and far between, and inevitably a big deal,’’ said Stephen J. Crimmins, a partner at the law firm K&L Gates and a former enforcement official at the SEC.
On May 18, its first day of trading, Facebook got off to a rocky start. Nasdaq delayed the start of trading and later flooded the market with shares, adding to investor trepidation.
Nasdaq’s lack of communication aggravated the situation, according to documents and executives, bankers, and regulators. On a May 31 call with the SEC chairwoman, Mary L. Schapiro, and other officials, Nasdaq’s chief executive expressed confusion about the SEC’s aggressive approach.
‘‘We’re regulators, too,’’ said CEO Robert Greifeld, adding ‘‘we’re all in this together.’’
The Facebook debacle comes after a flurry of trading breakdowns. In March, BATS Global Markets canceled its own IPO, after its systems faltered. Nasdaq last year halted trading in dozens of stocks amid technical problems.
Such experiences echo the so-called flash crash. On May 6, 2010, the Dow Jones industrial average plummeted more than 700 points in minutes, before recovering shortly thereafter.
In nearly every case, companies blamed technical malfunctions. But regulators say some breakdowns may point to more fundamental issues.
The SEC is also examining whether some exchanges give undue priority to high-frequency trading firms and big institutional investors through its order types and data disclosure.
The New York Stock Exchange is among the most prominent players facing scrutiny from regulators, who have opened two investigations into the Big Board, according to people briefed on the matter who spoke on the condition of anonymity because the cases are not public.
The SEC, the people said, is examining whether the New York exchange violated technical rules by distributing in-depth stock data to paying clients faster than the public received general information. The issue was first discovered in the rubble of the flash crash.
The exchange declined to comment. But people close to the exchange have attributed the problem to unintended technical shortcomings.