HEADLINE STOCKS-Some U.S. stocks on the move on July 6

(Updates to afternoon trading, adds Denbury, Green Plains, Spectrum, Smithfield and Sunoco)

NEW YORK, July 6 (Reuters) - Some U.S. stocks on the move on Monday:

DATA DOMAIN INC (DDUP.O)

EMC CORP (EMC.N)

NETAPP INC (NTAP.O)

EMC raised its all-cash offer to buy Data Domain to $33.50 per share. In addition, NetApp received all regulatory clearance to proceed with its proposed acquisition of Data Domain. [ID:nN06248956]

Shares of EMC rose 0.6 percent to $12.85 while Data Domain rose 2.7 percent to $34.10 and NetApp fell 1.5 percent to $18.67.

AMERICAN EXPRESS CO (AXP.N)

Stifel Nicolaus upgraded the credit card company to "hold," saying it was the least exposed to new rules on the sector because of its spend-centric model and low subprime exposure. [ID:nBNG124074]

Shares of the Dow component rose 5.3 percent to $23.46.

COVANTA HOLDING CORP (CVA.N)

The company said it would buy most of the North American energy-from-waste facilities of Veolia Environmental Services North America Corp in a cash deal worth $450 million. [ID:nBNG229968]

Shares fell 1.6 percent to $16.40.

SUNOCO INC (SUN.N)

The company will permanently shut the ethylene complex at its 178,000-barrel-per-day Marcus Hook, Pennsylvania, refinery due to insufficient demand, resulting in the layoff of 40-50 employees. [ID:nN06271112]

Shares sank 4.6 percent to $22.14.