Stocks that moved substantially or traded heavily Monday on the New York Stock Exchange and the Nasdaq Stock Market:
Family Dollar Stores Inc., up $15.08 to $75.74
The discount retailer is being bought for $8.5 billion by rival Dollar Tree, which is significantly broadening its reach as it looks to fend off Wal-Mart.
Trulia Inc., up $8.69 to $65.04
The real estate website operator is being bought by rival Zillow in a $3.5 billion all-stock deal expected to close next year.
Tyson Foods Inc., up $1.02 to $40.56
The meat processor reported a jump in quarterly sales and plans to sell its Mexican and Brazilian poultry units for $575 million.
Armstrong World Industries Inc., down $5.77 to $49.60
The flooring products and ceiling systems maker reported lower-than-expected quarterly profit and cut its full-year guidance.
Horizon Pharma Inc., down $4.75 to $9.15
The drug developer said two of its key products will be placed on exclusionary lists by the two largest pharmacy benefit managers.
AcelRx Pharmaceuticals Inc., down $4.44 to $6.39
The Food and Drug Administration rejected the company's painkiller-dispensing device Zalviso, partly citing data on shelf life.
Lincoln Electric Holdings Inc., up $3.28 to $70.05
The welding and cutting products company reported a better-than-expected second-quarter profit and declared a quarterly dividend.
Alliance Resource Partners LP, up $1.44 to $50.09
The coal mining company reported better-than-expected quarterly profit and revenue and increased its cash distribution.