Merck's

(MRK) - Get Report

plan to undercut competitors on price when Zocor loses its patent protection is "an attack on the generics, and it can succeed," Jim Cramer said on

CNBC'S

"Stop Trading!" segment Wednesday.

Teva

(TEVA) - Get Report

was down 10% Wednesday on the news. Cramer mentioned

Barr Labs

( BRL) as the kind of generic producer that is also vulnerable to such attacks.

"This could cut margins to shreds" among generics, Cramer said. "I don't want any part of it."

As for the broad rally in stocks Wednesday, Cramer credited

Morgan Stanley

(MS) - Get Report

and

FedEx

(FDX) - Get Report

, which both reported strong earnings. The two companies "touch every aspect of business."

On the other hand, investors should be paying more attention to

Best Buy

(BBY) - Get Report

, which earlier raised its dividend and expanded a stock buyback. "Stop yawning, start buying," Cramer advised.

Another company receiving praise was

Darden

(DRI) - Get Report

, whose casual dining restaurants aren't proving vulnerable to high gasoline prices. "I find it interesting that it costs more t to drive to Olive Garden than it does to eat at Olive Garden," Cramer said.

At the time of publication, Cramer had no positions in the stocks mentioned.

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