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Stocks volatile again after dismal January; Investors eye the next big jobs report; and the U.S. will hit the debt ceiling on Friday, but this time will be different

Hot Stock Minute

Stocks were volatile again on the first day of trading after a dismal January. The Dow Industrials closed down 5% for the month on a combination of concern about emerging markets, lackluster corporate earnings and an eye on China's slowing economy. This week, all eyes will be on the January Employment report which comes out Friday. Investors are hoping for a rebound after December's disappointing 74,000 jobs. The hope is that that was an anomaly and will be revised higher. Economists estimate that January will show a healthy gain of about 180,000 jobs.

Incoming Federal Reserve Chair Janet Yellen was sworn in at 9 am Eastern. Yellen’s tenure begins at a critical time, as the Fed winds down its massive bond-buying program. She will testify before Congress for the first time as Fed Chair next week when she delivers the Fed's semiannual monetary policy report and discusses the condition of the U.S. economy.

Also worth watching this week: whether consumers are still buying cars. January auto sales will be released today after a strong finish to 2013. On Wednesday, Twitter will deliver its first earnings report since going public in November. Analysts expect the company's revenue more than doubled in the quarter. Also on Wednesday, ADP will deliver its latest report on employment. Last month, the ADP report came in very strong ahead of the Labor Department's disappointing jobs report, confounding some economists. Thursday, General Motors reports earnings and Friday, of course, is the big one: the January jobs report.

Some stocks that were on the move in early trading today include Joseph A. Bank (JOSB). The stock was lower in early trading after the company resisted the latest takeover attempt by Men’s Warehouse. In the latest salvo in the raging takeover battle between the two men’s clothing retailers, Jos. A. Bank published a letter questioning the reaction anti-trust regulators would have to the proposed $2.3 billion dollar deal. Meanwhile, Jos. A. Bank is reportedly in talks to buy apparel retailer Eddie Bauer.

Yum! Brands (YUM) is set to report earnings after the close today. The parent company of Taco Bell, Pizza Hut and KFC is expected to post profits of $0.80 a share, which would be down $0.03 from the previous year. Revenue is expected to climb 2.5%. Investors will be watching closely to see how plummeting sales in China will effect Yum's earnings. Sales in China have fallen due to an avian flu scare as well as investigations into a chicken supplier for its KFC stores.

ArthroCare (ARTC) was up as much as 7% in early trading. Artificial joint maker Smith & Nephew is buying the Texas-based medical device maker for $1.7 billion in cash. Looking to boost its sports medicine business, Smith & Nephew will pay $48.25 a share in cash, 6.3% higher than ArthroCare's Friday closing price.

And Herbalife (HLF) was up more than 4% in early trading after the company raised its fourth quarter guidance and announced a $1 billion buyback.