LinkedIn (NYSE: LNKD) just made a nearly $300 million mistake with its IPO.

The social media giant priced its long-awaited IPO at $45 a share Wednesday, but opened at a stunning $83. With 7.8 million shares of stock up for grabs, LinkedIn made $351 million in its public offering to investors … but if it had priced the shares 84% higher with its initial sale of stock – at where it opened trading on Thursday morning – it would have raked in $647 million in capital instead.

In short, somebody made a fortune on this initial public offering. But it wasn’t LinkedIn.

Leaving cash on the table is a horrible truth for many companies that go public. LinkedIn was clearly afraid of selling itself short, as evidenced by a move Tuesday to up its IPO range 30% from $42 to $45. Executives sensed strong demand and did the math on 7.8 million shares, figuring they could rake in almost $30 million more with the move.

That $30 million now seems like just a drop in the bucket.

LinkedIn isn’t alone with its underpricing. According to Renaissance Capital IPO pricing data, about 27% of IPOs have priced above their proposed pricing range – meaning they could have demanded a higher share price at the get-go to generate more capital for growth.

Of course, that share price doesn’t always stick. Consider RenRen (NASDAQ: RENN), the hottest Chinese IPO this season. The company is called by many “the Facebook of China,” a fairly accurate description for the social media site with 160 million registered users. RenRen made a very auspicious debut — surging 28% from its $14 IPO price in the first day of trading on May 4, and RENN stock hit a high of $24.

However, RenRen now trades at about $13.80.

One could argue that RenRen’s offering was just about right. The profits made in the first few weeks by adept traders isn’t really a concern, since the company got a fair price for shares and left the stock market shenanigans to Wall Street sharks.

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It’s not outside the realm of possibility that LinkedIn could plummets a gut-wrenching 50% in the next few weeks to show executives were spot-on with their pricing. In fact, Silicon Valley expert Tom Taulli recommends the best way to buy LinkedIn stock is for savvy investors sit on their hands until the buying frenzy fades – then swoop up LNKD shares at a bargain.

But considering the stock opened at $83 and popped as high as $90 in early trading, there’s a very real chance LinkedIn may never again get back to the pre-priced level of $45 a share in the near future.

That’s tremendous news for the first shareholders of LNKD stock, many of whom likely traded out with a nearly 100% gain on their investment. But the high share price is a fact that will leave LinkedIn execs kicking themselves if they need an extra hundred million dollars to finance growth plans in the years to come.

Jeff Reeves is editor of InvestorPlace.com. As of this writing, he did not own a position in any of the stocks named here. Follow him on Twitter via @JeffReevesIP and become a fan of InvestorPlace on Facebook.