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Market Insider | What's Shaking | Earnings to Watch | Before the Bell

Check out which companies are making headlines before the bell on Wednesday:

UnitedHealth Group — The health insurer raised its quarterly dividend 32 percent to 28 cents per share, and also renewed its stock buyback program.

Apple — The International Trade Commission ruled that the AT&T versions of the iPhone 4 and iPad 2 violate patents held by Samsung. Apple plans to appeal the ruling.

Mattress Firm —The company reported first quarter profit of 38 cents per share, excluding certain items, two cents above estimates, with revenues also beating estimates. The mattress seller was able to improve its revenues despite a decline in same-store sales, as it opened new stores and acquired others.

Toyota — The automaker is recalling 242,000 Prius and Lexus hybrid models to fix a possible issue with braking systems.

Microsoft — Microsoft unveiled the latest version of its Windows 8 operating system, known as Windows 8.1, at a computer show in Taipei. The update will be rolled out later this year.

JPMorgan Chase — The bank will take an $842 million loss on the bankruptcy of Alabama's Jefferson County. JPMorgan is a major holder of debt related to the county's sewer systems.

Pandora — CFO Mike Herring is downplaying the potential competition from an Apple streaming radio product, which has been rumored but not yet announced. Pandora stock has fallen more than 15 percent over the past few days on those reports, yet Herring told a technology conference that Pandora will continue to compete against any "real or imaginary" competitor.

Citrix Systems — Goldman Sachs upgraded Citrix to "Buy" from "Neutral", citing an attractive risk/reward profile, which follows a sell-off in the shares since its April 24 earnings report.

Salesforce.com — Goldman added Salesforce to its "Conviction Buy" list, as it increases market share, with a potential 59 percent upside on the stock.

Dish Network — The satellite TV provider is disputing the objections raised by Sprint Nextel (S) to Dish's tender offer for Clearwire. Sprint is bidding for the portion of Clearwire it doesn't already own, and contends the Dish offer contains illegal provisions.

(Read More: See CNBC's Market Insider Blog)

—By CNBC's Peter Schacknow

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