Reuters - Markets roar back from the worst week in about four months - with wheeling and dealing giving investors the buy signal.

The Dow had its first triple-digit gain since earlier this month with the rally spread across all parts of the market.

The report is in and the numbers are in Herbalife's favor. A new auditor has taken a look at the books for 2010, 2011, 2012, and the nutrition company says it will not have to restate results. That further tips the scale in the battle of the billionaires. Carl Icahn and others have taken on Bill Ackman and his criticism of Herbalife as a pyramid scheme.

Shares of Herbalife rallying 9 percent.

Meanwhile, investors are still waiting to see if the Federal Reserve will start rolling back its bond-buying program at a meeting beginning Tuesday.

But for now it's all about the deal. Shares of Avago Technologies jumped nearly 10 percent and LSI Corp surged more than 38 percent as the two semiconductor companies tie-up in a $6.6 billion merger. Meanwhile, AIG rose more than one percent as it sells its aircraft leasing unit to AerCap Holdings for more than $5 billion. AerCap gained more than 33 percent.

Incoming economic data boosted investor sentiment including factory numbers in the U.S. Manufacturing output forged ahead for a fourth consecutive month.

Christmas is now just nine days away and a new survey continues to suggest this will be a less than jolly season for retailers. More than one-third of respondents in a poll say they plan to spend less than they did last year and just under a half say they plan to spend about the same. No matter how you look at the Bankrate.com survey, whether by age or income, the number of Americans planning to spend less outstrips those planning to spend more. Taking a quick look at the retailers: Walmart, one of only three Dow stocks down for the day; Best Buy and Amazon both shaking off jitters - ending with gains.

In Europe, a banner IPO for luxury outdoor apparel company Moncler, actually Italy's best IPO since 2010. Stocks in Germany, France, and the UK all up more than one percent.