If there’s one thing we’ve all learned in the aftermath of the financial crisis, it’s that stiffing your client is not a crime. Not if you’re an investment bank.

Deutsche Bank, according to a recent report by the Senate Permanent Subcommittee on Investigations, sold its clients subprime mortgage bonds that one of its own traders at the time described as “pigs.” Goldman Sachs took unseemly advantage of unsuspecting clients to offload its most toxic assets in 2007 and 2008. During the subprime bubble, this kind of behavior was par for the course.

It still is, apparently. On Thursday, LinkedIn, an Internet company that connects business professionals, became the first major American social media company to go public. The company had hired Morgan Stanley and Bank of America’s Merrill Lynch division to manage the I.P.O. process. After gauging market demand — which is what they’re paid to do — the investment bankers priced the shares at $45. The 7.84 million shares it sold raised $352 million for the company. For this, the bankers were paid 7 percent of the deal as their fee.

For a small company with less than $16 million in profits last year, $352 million in the bank sounds pretty wonderful, doesn’t it? But it really wasn’t wonderful at all. When LinkedIn’s shares started trading on the New York Stock Exchange, they opened not at $45, or anywhere near it. The opening price was $83 a share, some 84 percent higher than the I.P.O. price. By the time the clock had struck noon, the stock had vaulted to more than $120 a share, before settling down to $94.25 at the market’s close. The first-day gain was close to 110 percent.