It was enough to make your heart skip a beat. Shipboard spa operator Steiner Leisure (NASDAQ:STNR) opened at $18.46 on Friday, well below the $34.28 price it had last fetched a day earlier.

Had the company posted a heartbreaking quarter? Had Steiner lost a contract with a major cruise line? Had the Surgeon General warned that being pampered with spa treatments could be hazardous to your health? No, no, and heck, no.

The problem, apparently, was with a market maker that experienced technical problems that morning. (A market maker is a firm that facilitates the exchange of shares by allocating the bid and ask price for specific stocks or equities.) Two minutes into the new trading day, all was right in the world. Steiner was back in the $34 range.

A simple mistake? There is no such thing. If you're not familiar with Steiner Leisure, it's been a very popular stock in certain Foolish circles. Since the stock was recommended in the November issue of our Rule Breakers newsletter service, the company's stock has appreciated by a stellar 61%.

Healthy earnings growth and an enviable track record of topping analyst estimates for a dozen straight quarters will do that to a quality company like Steiner. But some investors, not wanting to be too greedy, had stop-loss orders tied to their positions in Steiner. So, in the event that the stock dipped a bit, their orders would be executed, and they would be able to walk away with what would still be respectable gains.

Well, going by the exchange of experiences taking place in our Steiner Leisure discussion board (yes, every recommended stock gets its own dedicated board), that one market-maker mistake triggered more than a few stop-loss orders when the stock, erroneously, opened in the teens.

Steiner wasn't alone, though its case was one of the most severe of the two dozen companies that were temporarily roughed up by the malfunction. Shoe specialist Madden (NASDAQ:SHOO) opened 17% lower. Market research firm Value Line (NASDAQ:VALU) earned its corporate moniker when it opened 38% lower. Nature's Sunshine (NASDAQ:NATR) went from dawn to dusk when it opened 33% lower.

Nasdaq (NASDAQ:NDAQ)? Its own shares were unscathed by the glitch, but it acted quickly because it knew that its reputation was at stake. As the day progressed, it looked into the problem. By Friday night it had agreed to break any trades that took place at prices that were more than 15% below the previous day's close.

That certainly isn't going to make anyone who suffered through a stop loss that was triggered under false pretenses feel any better about the whole ordeal. Bad show, Mr. Market. Then again, Mr. Market, I guess you're only human.

Need some more reading while you lie out on the massage table?

Longtime Fool contributor Rick Munarriz was the one who recommended Steiner Leisure last year. However, he does not own shares in any of the companies mentioned in this story. The Fool has a disclosure policy. He is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early.