What a Week: Role Reversal

If last week was about selling energy and materials to buy tech, this week was the mirror image.

In a seemingly illogical turn of events, the tech sector stumbled despite strong earnings from several bellwether companies, while energy was the best-performing sector amid plunging oil prices. The sum of the parts was a lot of volatility, investors getting the usual jitters about earnings, and blue-chip indices and bond yields that were flat on the week. The Nasdaq Composite, conversely, did not emerge unscathed.

Apple(AAPL Quote) led the Nasdaq to a new six-year high last week, and just as swiftly led the index's 2.1% plunge in this round. Enthusiasm for the iPhone faded as investors gathered anxiety about CEO Steve Jobs and the government's investigation into options backdating. Shares of Apple fell 7.6% on the week. Investors also debated the strength of Apple's midweek earnings report. The company beat estimates but provided its usual dose of conservative guidance.

The same was true for Intel(INTC Quote), which also beat earnings estimates earlier this week, yet warned that its profit margins would be stunted throughout 2007 due to its price war with competitor Advanced Micro Devices(AMD Quote). Shares of Intel and AMD fell 5% and 12.1%, respectively. IBM couldn't catch a break, despite an impressive quarter as well. Big Blue's shares slid 2.5% on the week, and Cisco's(CSCO Quote) fell 6.7%.