Stocks that moved substantially or traded heavily on Monday:
Sotheby's, up $20.74 to $56.13
The New York auction house is being sold to French Israeli businessman Patrick Drahi for almost $3.7 billion.
Array BioPharma Inc., up $16.85 to $46.44
Pharmaceutical company Pfizer is buying the cancer treatment developer for $10.6 billion.
C&J Energy Services Inc., up $2.15 to $12.87
The oilfield services company is being bought by rival Keane Group in an all-stock deal.
Tyson Foods Inc., down $3.38 to $78.53
The food maker lagged the market as investors moved away from safe-play holdings in the consumer staples sector.
UniQure NV, up $8.59 to $81.14
The gene therapy developer is considering putting itself up for sale, according to media reports.
LegacyTexas Financial Group Inc., up 66 cents to $38.88
The bank is being sold to U.S. regional bank Prosperity Bancshares for $2.1 billion in cash and stock.
Facebook Inc., up $7.68 to $189.01
The social media company gained ground as investors shifted to more risk-heavy internet and technology stocks.
Align Technology Inc., down $17.02 to $288.68
The medical device company and Straumann Group ended discussions over a potential distribution deal.