Although we don't believe in timing the market or panicking over daily movements, we do like to keep an eye on market changes -- just in case they're material to our investing thesis.

As the Federal Reserve's chairman Ben Bernanke is expected to hold a press conference later today and tell the world whether or not tapering of its bond buying program will begin this month, stocks have slowed down on their rally this week. As of 12:45 p.m. EDT the Dow Jones Industrial Average (DJINDICES:^DJI) is down 54 points, or 0.35%. The S&P 500 is off by 0.21%, and the NASDAQ is 0.2% lower. With so much uncertainty about what the Fed will do today, investors seem hesitant to make any big moves prior to the press release, but be assured the fireworks go off once Fed Chairman Ben Bernanke begins speaking.

Furthermore, as the markets as a whole move lower, a number of big losers can be found within the Dow today. Shares of UnitedHealth are leading the way lower, down 2.1% as investors try to determine whether the Obamacare Exchanges will be good or bad for the health insurance providers.

Another big loser is Procter & Gamble (NYSE:PG), which is off by 1.4% this afternoon after an analyst at Barclays cut the rating on the stock from "overweight" to "equal weight." The analyst noted that while P&G has performed well, the stock price will likely tread water until the company comes up with a plan to grow revenue and profit at a faster rate. Investors shouldn't concern themselves with this, though, as the company is working on boosting growth and paying investors a nice 3% dividend yield while they wait.

The Dow's telecom heavies are also in the red. AT&T (NYSE:T) and Verizon (NYSE:VZ) have fallen 0.8% and 1%, respectively, after rumors began circulating that Sprint (NYSE:S) will soon announce its own plan to combat its competitors' plans to allow customers to upgrade phones on a faster cycle than the traditional two-year period. While this was initially a way for one of the top U.S. carriers to set itself apart from the crowd, all it may end up doing is lowering margins and profits for the operators as they all fight for market share.  

Fool contributor Matt Thalman has no position in any stocks mentioned. Check back Monday through Friday as Matt explains what caused the Dow's winners and losers of the day, and every Saturday for a weekly recap. Follow Matt on Twitter @mthalman5513

The Motley Fool recommends Procter & Gamble and UnitedHealth Group. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.