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 of 2:35 p.m. EST the Dow Jones Industrial Average (DJINDICES:^DJI) is down 124 points, or 0.79%, after closing at an all-time high yesterday. Today's slide comes despite decent unemployment claims numbers and a Bureau of Economic Analysis estimate of 2.8% gross-domestic-product growth in the third quarter. The likely cause of the decline is coming from across the pond, where the European Central Bank again lowered interest rates. This move is a clear indication that Europe is still struggling to recover from its most recent recession and needs an additional jolt to get back on track. Furthermore, this is a sign to investors that the multinationals that rely on Europe may continue to experience weak growth from that region.

Europe is not the only reason the Dow is moving lower today, as 24 of the index's 30 components are trading in the red at this time. Let's take a look at three of the biggest losers.

Shares of Microsoft (NASDAQ:MSFT) are down 1.8%. It appears investors are taking money off the table, as the stock rose 4.2% yesterday and is up more than 31% over the past 52 weeks. A sell-off after a big run like yesterday's, or even the past year's, year shouldn't shock Microsoft investors who have been with the company for a long time, as the stock has gone nowhere for the past 15 years:

MSFT Chart

MSFT data by YCharts.

While the stock has performed well this year, Microsoft is facing a lot of headwinds: the search for a new CEO, the acquisition and integration of Nokia's handset business, weak PC sales hurting Windows revenue, and a lack of major mobile presence in a world that seems to be more and more on the go. While I'm not saying shareholders should sell (I, for one, am not selling), I can't blame those who are.

Another big loser today is Goldman Sachs (NYSE:GS) which is now down 1.7%. The drop follows an announcement that its foreign-exchange-trading activities are under investigation at home and abroad. The company disclosed the information in its 10-Q filing released this morning, making Goldman the seventh global bank under investigation by U.S. and European authorities that believe traders at these firms colluded and manipulated exchange rates. Furthermore, the Department of Justice and the Commodity Futures Trading Commission are looking into allegations that these banks used inside information about large exchange transactions to affect rates.  

Lastly, AT&T (NYSE:T) is down 1.7% amid news that it will pay $3.5 million to settle a charge brought by the federal government. The wireless provider allegedly overbilled a U.S. government fund that is intended to help those with hearing and speech impairments. While this is certainly not the kind of news investors want to hear, it's a small amount of money for a company like AT&T and will not have a material effect on the business. Thus investors shouldn't be selling based on this news.  

Fool contributor Matt Thalman owns shares of Microsoft. Check back Monday through Friday as Matt explains what causing the big market movers of the day, and every Saturday for a weekly recap. Follow Matt on Twitter @mthalman5513

The Motley Fool recommends Goldman Sachs. The Motley Fool owns shares of Microsoft. 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.