"Past performance is often negatively correlated with future relative performance," he said. Of course, some bulls say it's too soon to pull out of tech names, noting that the best upward earnings revisions tend to come from the information technology sector. This week, Smith Barney analyst Tobias Levkovich recommended that investors buy Intel ( INTC ), Cisco ( CSCO ), Novellus undefined and Jabil Circuits ( JBL ). Still, Levkovich acknowledged that if "exogenous shocks occur" or corporate confidence is shattered, say, from continued joblessness, optimistic earnings projections for this year and next could be revised lower. That would put a stock like Novellus -- which currently trades at a P/E of 50 based on next year's earnings -- at considerable risk. As originally published, this story contained an error. Please see Corrections and Clarifications.