What a Week: Clouds Part

And near the week's end, private equity firm Blackstone Group filed for an initial public offering, suggesting that one of the world's premier shops for valuing companies was satisfied with a near $40 billion valuation for its own operation. Some worry that what looks like an "exit strategy" for Blackstone means a top for the market, but the filing itself didn't do any harm.

The Dow Jones Industrial Average gained 3.1% on the week, putting it back into the green for the year. The Dow is now up 0.1%, or 17 points, year to date.

The S&P 500 added 3.5% over the five days, marking its best week in four years. The Nasdaq Composite also surged 3.5% this week.

"In a decidedly positive reversal, each of 10 sectors and all 64 industries within the S&P 1500 posted positive gains this past week," writes Brian Belski, U.S. sector strategist at Merrill Lynch. The top three performing sectors, according to Belski, were energy, telecommunications and utilities.

Energy stocks outperformed in conjunction with an 8.9% jump in oil prices on the week. Shares of the Oil Services HOLDRs (OIH Quote) exchange-traded fund jumped 5.7% on the week, while Exxon Mobil(XOM Quote) and Chevron (CVX Quote) added 7.4% and 8.4%, respectively.

Other economically sensitive parts of the market also outperformed. The Dow Jones Transportation Average gained 2.9% this week, while the Morgan Stanley Cyclical Index advanced 3.2%.