A little helium escaped the balloon that's filled with high hopes that a new round of quantitative easing will invigorate the U.S. economy today. That was, of course, before oil prices fell off a cliff, down as much as $4.33 per barrel, on very heavy trading. The impetus for the drop appears to be renewed talk about releasing oil from the U.S. strategic reserves to help drive the price down, although any effect would probably be short-lived. For the day, the S&P 500 (INDEX: ^GSPC) finished down 4.58 points (0.31%) to 1461.19. Let's take a look at four companies that helped move the S&P 500 today.

Companies that helped the S&P 500
Biotech giant Gilead Sciences (Nasdaq: GILD) had an exceptionally good day, up 6%, after an analyst at JPMorgan Chase raised his price target for the stock and the sales forecast for Gilead's recently approved four-in-one HIV pill, Striblid. JPMorgan expects Striblid sales could reach $2.9 billion by 2015. Between its newly improved HIV drug and the success it's received in clinical trials with hepatitis-C drug hopeful GS7977, Gilead looks to be in great shape.

Chipotle Mexican Grill (NYSE: CMG) is hot, hot, hot again following comments from research firm ITG Research, which anticipates Chipotle's same-store sales are tracking higher by 5.5% to 7.5% versus Wall Street's current estimate of 4.9%. Chipotle ran into issues this summer, when it reported higher expenses and slower customer traffic; however, ITG's research could speak otherwise. My Foolish colleague Alyce Lomax would tend to agree, having made Chipotle a Rising Star buy in her real money portfolio. Chipotle wrapped the day up 3%.

Companies that hindered the S&P 500
It was lights out again for Netflix (Nasdaq: NFLX) today, down nearly 6%, after brokerage firm Macquarie started the online video-streaming company with an "underperform" rating and a $50 price target. Macquarie notes that media companies hold the upper hand in negotiations, not content providers like Netflix. In addition, competition between Amazon.com and Netflix for content contracts has been fierce and will probably lead to tougher times ahead for Netflix.

Following its recent huge run-up, solar-panel manufacturer First Solar (Nasdaq: FSLR) took a breather, down 5.6%, after a rival, Suntech Power, drastically cut production. LDK Solar also announced it's in talks with investors to potentially raise capital. Although a reduction in solar output should alleviate some competition and pricing pressure for First Solar, it continues to speak to the weak demand that permeates the sector.

Is it lights-out for solar?
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