Apple, Facebook are big market movers

NEW YORK Stocks that moved substantially or traded heavily Monday on the New York Stock Exchange and the Nasdaq Stock Market:

NYSE

KB Home, up $1.28 at $18.19

Citigroup removes its "Sell" rating on the homebuilder, citing a recovery in earnings.

Darden Restaurants Inc., up $3.26 to $54.35

Activist investor Starboard Value disclosed a sizeable stake in the restaurant operator and is expected to push for a breakup.

Nasdaq

Apple Inc., up $21.07 to $570.09

The tech giant announced a long-anticipated agreement with China Mobile to bring the iPhone to the world's biggest phone company.

Facebook Inc., up $2.65 at $57.77

The social networking company's shares hit a new all-time high, helped by a bullish note from a Cantor Fitzgerald analyst.

Ariad Pharmaceuticals Inc., up 57 cents to $7

The drugmaker jumps for the second consecutive day after getting regulatory approval to put its leukemia drug back on the market.

YRC Worldwide Inc., up $3.28 to $18.25

The trucking company reached a deal to cut its debt by about $300 million.

Skullcandy Inc., up 71 cents to $6.75

Roth Capital Partners upgrades the audio company, believing that initiatives by new management are starting to pay off.

United Therapeutics Corp., up $26.67 to $114.51

Regulators approved the drugmaker's treatment for high blood pressure, Orenitram, which was a surprise to some market analysts.