Costco and Hess slide while Omega Protein climbs

Stocks that moved substantially or traded heavily on Friday:

Costco Wholesale Corp., down $9.87 to $157.09

Analysts said they were concerned about the warehouse club operator's profit margins and rates of membership renewal.

Synchronoss Technologies Inc., UP $3.43 TO $14.15

The mobile services company renewed talks with Siris Capital, which says it is interested in buying Synchronoss' Intralinks business.

Hess Corp., down 92 cents to $44.59

Oil prices and energy companies tumbled as Tropical Storm Nate moved toward the U.S. Gulf Coast.

Omega Protein Corp., up $5.45 to $22.05

The nutrition product company said it will be bought by Cooke Aquaculture for $22 a share, or $494 million.

Haverty Furniture Cos., down $2.80 to $24.20

The furniture company reported weaker third-quarter sales than analysts had forecast.

Gigamon Inc., down $3 to $40.55

Reuters reported that Elliott Management's effort to buy the technology company has stalled.

Yum China Holdings Inc., up 85 cents to $40.82

The restaurant company reported a smaller-than-expected quarterly profit but strong sales.

Helen of Troy Ltd., down $9.30 to $87.80

The personal and household products company lowered its sales forecast for the year.