Lehman's

(LEH)

post-earnings conference call might have been reason to "sell in May and go away," Jim Cramer said on

CNBC's

"Stop Trading!" segment Monday.

While headlines emanating from Lehman's second-best quarter ever were positive, the tone of the call was different, with May seeming "horrible," thanks to the

Federal Reserve

.

Elsewhere, Cramer said rumors are circulating that a big Wall Street firm will turn positive on personal computer stocks such as

Dell

(DELL) - Get Report

and

Intel

(INTC) - Get Report

in the next 24 hours, and turn negative on wireless names such as

Nokia

(NOK) - Get Report

,

Texas Instruments

(TXN) - Get Report

and

RF Micro

(RFMD)

. Cramer said he belives the momentum is still in wireless but wanted to pass along the tip.

Houston Exploration

(THX)

looks cheap the same way

Kerr-McGee

(KMG)

and

Marathon

(MRO) - Get Report

previously were.

"People are dumping stocks at six times earnings, I guess they think they're going to three times earnings. History shows that that is a fool's bet," Cramer said.

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

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