Starting the day in the black, the S&P 500 Index (SNPINDEX:^GSPC) took a turn for the worse on Monday, ending 5 points, or 0.33%, lower to close at 1,551. While the catalyst for the decline was a small country in the Mediterranean, these three S&P companies would have fallen, Cyprus or no Cyprus, which helped to make them the worst performers in the entire index today.

Oftentimes your biggest strength can also be your biggest weakness; for eBay (NASDAQ:EBAY), its blessing and curse happens to be PayPal, the payments system it controls. Shares of the online auction leader fell 3.7% after an analyst (who jumped the gun a bit -- eBay’s "analyst day" is Thursday) questioned new fees by major credit card providers. The increased fees are bound to attract some inquiries at analyst day, since the effect on PayPal’s margins are, as of yet, unknown. 

Oh, to be an analyst! Red Hat (NYSE:RHT) also slipped 3.6% on an analyst downgrade from "outperform" to "market perform" today. The open-source operating-system provider isn’t even doing poorly; the Raymond James (NYSE: RJF) analyst simply thinks Wednesday's quarterly results won't much exceed what Wall Street already expected. It's odd that Red Hat should fall on expectations that it will meet expectations (did investors expect results to exceed expectations?), but such is the logic of the market at times.

Lastly, shares of First Solar (NASDAQ:FSLR) fell 2.9% as the solar industry suffered through a rough day. JA Solar Holdings (NASDAQ: JASO) ruined it for the group, after it reported a widening quarterly loss. While the future of solar energy is indeed (pardon the corniness) bright, like any emerging area it's tough to tell at an early stage which companies will succeed and which will wither and die. Shares of First Solar, which are 43% more volatile than the overall market, are especially vulnerable to signs of the industry's health, and the news today that JA Solar's losses were due to weakening global demand doesn't bode well for business.