Wall Street's performance today resembled a roller coaster, as markets digested and traded on each successive word of Federal Reserve Chairman Ben Bernanke's session with the Senate. Unfortunately, the resemblance was generally limited to the rapidly descending part of the roller coaster. The S&P 500 Index (SNPINDEX:^GSPC) slumped 13 points, or 0.8%, to close at 1,655. The three worst performers in the S&P, however, saw much more pronounced drops.

For starters, First Solar (NASDAQ:FSLR) shares cratered 5.8% Wednesday. With the stock price having nearly quadrupled in the last year alone, today's big losses don't seem quite as massive. In fact, the stock had even rallied 12.5% in just the previous three days of trading before today, as a rival solar company beat quarterly expectations. Wednesday's losses look like typical profit-taking, although the company has lamented recently that obtaining capital to finance growth is a major challenge.

Allegheny Technologies (NYSE:ATI), a big player in the metals market, slipped 4.7% Wednesday in a very similar situation to the short-term sell-off First Solar experienced. Having posted major gains for three straight days, Allegheny shares sold off steeply in what appeared to be indiscriminate selling based on Bernanke's speech. The company, which sells metals ranging from alloys to titanium to steel, provides materials to industrial companies, the worst performing sector of the market today.

Lastly, Apollo Group (NASDAQ:APOL) dropped 4.1% Wednesday. The for-profit education company, which runs the University of Phoenix, simply operates in an area where growing profits isn't very easy to come by. After posting nearly flat earnings in 2011, earnings slumped more than 30% in 2012 as revenue took a 10% beating. The government is tightening up on standards for student loans, which spells trouble for Apollo's entire business model.

Fool contributor John Divine has no position in any stocks mentioned. You can follow him on Twitter, @divinebizkid, and on Motley Fool CAPS, @TMFDivine.

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