The roller-coaster ride on the markets continued this week. The Dow Jones Industrial Average (DJINDICES:^DJI) moved lower one day and higher the next during this past four-day trading week. When all was said and done, the blue-chip average was up 0.45%, or 66 points, and now rests at 14,578. The Nasdaq also has a winning week and gained 22 points, or 0.69%. But the real index winner was the S&P 500, which rose 0.79% and set a new all-time closing high on Thursday.

Even though the Dow managed to put together anther winning week, nine of the index's 30 components ended the trading week in the red.

Before we hit the Dow losers, let's look at the index's big winner: UnitedHealth (NYSE:UNH). Shares of the health-care provider rose by 5.05% during the short trading week, mainly because many market participants believe the previously lowered Medicare Advantage reimbursement rates will be readjusted higher. Medicare is a major revenue stream for UnitedHealth, and any reductions would hurt profits, while any increases could really boost earnings.  

The big losers
The issues in Europe played a large role in what happened to U.S. stocks this past week, with financials getting hit the hardest. With all the fears and concerns about possible bank runs in Europe, it's no wonder Bank of America (NYSE:BAC) was the worst-performing Dow component last week. Shares of JPMorgan Chase weren't far behind in a week that was brutal to the banking industry.

Bank of America lost 3.02%, while JPMorgan fell 2.7%, making it the second worst performing Dow stock. Every single day this past week, the banks were the big losers, and for most days it was simply due to the situation in Cyprus. But on Tuesday, Bank of America fell more than its counterparts, possibly because of a Bloomberg report indicating that Bank of America's Merrill Lynch unit in London had lost a top employee. Derek De Vries, the head of European bank equity research for the company, is reportedly no longer with the firm, but a news conference or press release never came from B of A pertaining to the departure.

Something seems fishy here. The head of the European bank equity research team is all of a sudden no longer with the company -- and at a time when the banks in Cyprus need a bailout, and as concerns linger that other European nations may need additional help as well? The fact that this move wasn't announced almost makes it seem as if the bank if attempting to hide something.

On Wednesday, meanwhile, JPMorgan fell nearly twice as far as the other banks because of a report that the officials investigating the Bernie Madoff Ponzi scheme are now looking into the bank and its role in the situation. As of now, it's unclear whether the bank completely followed the law when it comes to filing all the proper documents with regulatory agencies. If it excluded documents that may have helped regulators uncover the Ponzi scheme sooner, the bank will be in a world of hurt and will probably have to pay some hefty fines. 

In other news, shares of Chevron (NYSE:CVX) lost 1.94%, coming during a week when the company's board of directors imposed some financial penalties on Chevron's top management team for an unsatisfactory safety record in 2012. The company was plagued with problems this past year -- a small oil leak from a burst pipeline in Utah, another oil leak in Brazil, a fire that burned for weeks off the coast of Nigeria, and another fire at the refinery at Richmond, Calif. 

The board's decision to reduce compensation over these issues should serve as much-needed a kick in the pants to Chevron's top brass. As we saw with the BP Gulf oil spill, one big mistake can hurt a company for years, not just months or days.

Another big loser this week was General Electric which saw its shares decline 1.07%. It was a rather quiet week for GE, but on Monday, Bloomberg reported that if Blackstone steps in to help take Dell private, Dell Financial may be sold to GE. Whether GE would want it is unknown, but the company could probably incorporate it easily into the GE financial arm. While the deal would perhaps make sense for all parties, my biggest concern at this point would be how much liability the acquisition would tack on to GE's current $414 billion in debt.  

Other Dow losers this week were 3M, which closed lower by 0.1%; Procter & Gamble, down 0.27%; Caterpillar, down 0.58%; Du Pont, down 0.22%; and United Technologies, down 0.17%.