Premarket roundup: Teledyne, Amgen

Among the premarket stories for Monday, July 28, from AP Financial News:

NEW YORK (AP) _ A Jefferies & Co. analyst downgraded aerospace and energy contractor Teledyne Technologies Inc. Monday, saying the shares are fully valued.

NEW YORK (AP) _ Shares of Amgen Inc. surged in premarket trading Monday after the company reported positive trial results for its osteoporosis drug candidate denosumab _ which one analyst terms "a future blockbuster."

NEW YORK (AP) _ A Lehman Brothers analyst downgraded the alternative fuels sector and two ethanol stocks Monday, saying a fall in corn prices has not led to a rise in margins.

NEW YORK (AP) _ The business environment for recreational vehicle makers, already weakened by a sluggish economy and high gas prices, is likely get worse before it gets better, an analyst said Monday.

NEW YORK (AP) _ Analysts offered conflicting views on Goodrich Corp. Monday after the maker of aerospace and defense products reported better-than-expected second-quarter earnings.