Midday movers: Wynn Resorts, Intuitive Surgical, Darden & more
Darden Restaurants rose. In an investor presentation, Starboard, one of the company's biggest investors, outlined its "serious concerns" with the proposed spin-off of its Red Lobster unit.

Intuitive Surgical surged after the company said the FDA cleared the U.S. introduction of its newest da Vinci surgical system.

Casino stocks Wynn Resorts , MGM , and Las Vegas Sands moved higher as Macau gaming revenue grew a better-than-expected 20 percent in the first quarter.

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

Medicines Company moved lower after the company said a federal judge in Delaware upheld two patents related to Hospira's generic version of Medicines Co's angiomax product.

Big name tech stocks Google , Microsoft , and Cisco Systems helped to lead the Nasdaq higher.

Priceline gained ground. The company changing its name to the Priceline Group.

General Motors moved higher. CEO Mary Barra is scheduled to testify on Capitol Hill about the company's ignition switch problems that have led to 13 deaths.

Citigroup climbed. The company said it fired two bond traders at Mexican unit Banamex last year for violating their code of conduct. Reuters reported that the two were engaged in unauthorized trades that cause paper losses worth millions of dollars.

Ford gained after the automaker's March vehicle sales rose a better-than-expected 3.3 percent. Toyota also rose after the Japanese automaker's March sales increased by a better-than-expected 4.9 percent.

Caterpillar advanced as executives from the company head to Capitol Hill to explain its strategy to avoid paying billions of dollars in U.S. taxes.

Pandora rose after Canaccord Genuity repeated a "buy" rating and $43 price target, saying March ad load suggest a strong first quarter.

Marvell hit a two-year high as all the rulings in its long-running patent case with Carnegie Mellon were made. While final damages were put at $1.54 billion, Nomura said the rulings were less damaging than feared.

Rubicon jumped after JPMorgan upgraded the stock to "outperform" and boosted its price target by $2 to $14 a share.

GlaxoSmithKline fell after the FDA found contamination of drug ingredients made at a plant in Ireland and said the drugmaker didn't take sufficient action to fix the problems.

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