Family Dollar, Trulia, Horizon Pharma, Tyson Foods, and AcelRx are big market movers

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

NYSE

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.

Nasdaq

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.