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.

In a holiday-shortened week, the Nasdaq suffered its worst showing since last June, while the S&P 500 put in its worst showing since May 2012, and the Dow Jones Industrial Average (^DJI -0.93%) hadn't seen such a bad week since November 2011. The Dow lost 579.45 points, or 3.52%, as the S&P 500 fell 48.41 points, or 2.63%, and the Nasdaq slid 69.41 points, or 1.65%. The bulk of the declines came on Thursday and Friday, with Thursday's news that China was experiencing its first manufacturing slowdown in nearly six months causing investors to pull funds from emerging markets. That just made a bad week worse.

But it wasn't all bad news in the markets. Even as 28 of the Dow's 30 components fell, Microsoft (MSFT -0.74%) managed to rise 1.15%, making it the index's biggest winner of the week. Investors reacted positively to the company's quarterly earnings, which came out Thursday after the closing bell. Sales of $24.5 billion and earnings per share of $0.78 beat analysts' estimates, as the company's Xbox unit really delivered: Microsoft moved a combined 7.4 million Xbox One and 360 units, compared with 5.9 million the previous year. The Surface tablet finally seems to be catching on, too, as the company doubled its sales within that unit to $893 million. Investors were no doubt relieved to see Microsoft can keep growing its revenue, and the positive trend looks as though it should continue.  

Last week's big losers
The last time the Dow's biggest loser for the week lost more than 5% was the last week of November, when Cisco lost 5.8%. But this past week, even the third-place loser lost more than that, as shares of Travelers (TRV -7.76%) fell 5.91%. The company reported solid earnings early in the week, with net income more than tripling from a year ago to hit $2.70 per share as the company's catastrophe payout fell from more than $1 billion a year ago to just $53 million this past quarter. But investors were concerned with the company's deteriorating margins this past quarter, and shares declined for the remainder of the week.  

The second worst performing Dow component was General Electric (GE 0.21%). The bulk of its 6.13% drop for the week came on Friday, as investors began to express concern for the overall health of the world economy. GE not only operates all around the world but also needs large and expensive infrastructure projects to grow revenue, so for GE, a slowing world economy equates to a coming revenue slowdown. Still, investors should keep in mind that the economic report out of China is the only recent indication we have that major economies might be slowing. In other words, a slowdown is just speculation at this point. GE investors would be wise to sit tight and wait another few months to see how things play out.

Finally, this past week's biggest Dow loser was DuPont (DD), down 6.32%. DuPont's decline wasn't due to a company announcement, a ratings downgrade, or a big contract signed by a competitor. As with GE, it appeared to be investor fear over the global economy. Over the past few years, as DuPont has sold off parts of its business and increased its focus on other areas, it has positioned itself to be more dependent on positive economic conditions. The combined news that China may be slowing, that the Federal Reserve may taper more of its asset purchase program, and that emerging markets are weakening sent DuPont's shares tumbling.  

The other Dow losers this week:

  • 3M, down 5.16%
  • American Express, down 4.41%
  • AT&T, down 0.83%
  • Boeing, down 2.71%
  • Caterpillar, down 5.76%
  • Chevron, down 2.51%
  • Cisco, down 2.37%
  • ExxonMobil, down 4.34%
  • Goldman Sachs, down 4.9%
  • Home Depot, down 2.27%
  • Intel, down 4.02%
  • IBM, down 5.49%
  • Johnson & Johnson, down 4.68%
  • JPMorgan Chase, down 5.19%
  • McDonald's, down 0.52%
  • Nike, down 2.49%
  • Pfizer, down 3.21%
  • Procter & Gamble, down 0.87%
  • Coca-Cola, down 1.12%
  • United Technologies, down 2.11%
  • UnitedHealth, down 1.26%
  • Verizon, down 1.48%
  • Visa, down 4.7%
  • Wal-Mart, down 2.32%
  • Walt Disney, down 1.87%