HEADLINE STOCKS-Some U.S. stocks on the move on July 9

(Updates to afternoon trading, adds Helen of Troy, 3Com, YRC Worldwide, SunTrust, KB Home, IBM, Equifax and TiVo/Best Buy. Updates Merck, Broadcom/Emulex)

NEW YORK, July 9 (Reuters) - Some U.S. stocks on the move on Thursday:

ALCOA INC (AA.N)

The aluminum company late Wednesday reported a second-quarter loss that was narrower than expected, helped by cost-cutting measures. [ID:nN08471164]

Shares of the Dow component gained 0.2 percent to $9.48.

MERCK & CO (MRK.N)

Shares of the Dow component sank 3.7 percent to $26.99. The stock was pressured amid speculation its Zetia cholesterol medicine fared poorly in a clinical trial comparing it with Abbott Laboratories' (ABT.N) Niaspan.

CITIGROUP INC (C.N)

The company announced a number of management changes, including the departure of Gary Crittenden, the chairman of Citi Holdings, from the company. [ID:nN09445304]