Just two points from all-time closing highs, the S&P 500 Index (^GSPC -0.03%) latched onto falling jobless claims today, rallying 8.7 points, or 0.56%, to close at 1,563. The index's advances have been unusually steady recently, with confidence slowly returning to the markets. Quite contrary to the spirit of the moment, the following three S&P members were anything but steady today, for a variety of reasons.

I'll be the first to admit that a technologically savvy infant with fully developed vocal chords and linguistic skills is, in all likelihood, a financial genius. But today's 8.2% decline reminds me that the E*TRADE (ETFC) baby simply cannot be old enough to have seen a full market cycle. Nor can the adorable cradle-bound young'un be expected to know how to soothe hedge funds, which is a useful skill: The online brokerage's largest shareholder is set to sell just under 10% of E*TRADE's total outstanding shares next Tuesday. That's not insubstantial, baby.

Rising costs at a Canadian iron ore pellet plant forced Cliffs Natural Resources (CLF -4.43%) to announce plans to pause production at the location today. Capital-intensive businesses like Cliffs are extremely susceptible to closures like today's, where infrastructure is already in place, but must be left unused or awkwardly transported. Citing prohibitively high extraction costs per ton about 20% higher than another of its Canadian locations, the stock slumped 4.5% on the news.

Maker of the robotic medical device da Vinci, Intuitive Surgical (ISRG -0.52%) stumbled 3.8% Thursday after attempting to smooth things over with shareholders about federal safety inquiries. Pointing a finger at a change made in reporting practices rather than issues with its product, a company statement reassured the public that no one, after all, has been reported dead or injured as a result of device malfunction. But that claim is legally controversial, as 30 people died in 2012 in operations done with the machines. Shares have taken a nearly 15% haircut since reports surfaced that the FDA was investigating the company.