Midday Movers: CMG, CI, GM & More

Take a look at some of Tuesday's midday movers:

Chipotle sank after hedge fund manager David Einhorn said he was shorting the stock because its valuation made no sense, speaking at Value Investor Congress.

(Read More: Pros Say Weak Earnings Season Ahead)

Cigna rose after Einhorn said he was bullish on the stock, saying it was a better investment bet than other HMO stocks.

GM rose after Einhorn said he was bullish on the company, calling the stock an "ugly duckling."

Green Mountain rose despite Einhorn’s criticism of the company, in part saying the company’s audit committee moved too quickly and fell short on its job.

Zillow sank after the SEC asked for added disclosures.

MetroPCS surged on reports that the telecom company is close to a deal with Deutsche Telekom’s T-Mobile unit. Sprint fell following the news.

Illumina rose on a London Times report that Roche made another bid for the company.

Acuity Brands fell following weaker-than-expected earnings and lukewarm guidance.

PVH gained ground after the company raised its full-year profit forecast, citing strength in its Tommy Hilfiger business and Calvin Klein clothing lines.

Mosaic lost ground after the fertilizer maker posted a lower-than-expected quarterly profit as phosphate sales plummeted.

Express slid after the clothing chain’s earnings came in below Street expectations.

(Read More: CNBC's Market Insider Blog)

—By CNBC's Rich Fisherman.

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