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.

For the past week, the stock market has been stuck in a vicious cycle of negative sentiment. Investors have faced the troubling prospects of a federal government shutdown and continued discord among lawmakers about key issues like the budget and Obamacare. At the same time, though, the economy has shown signs that it's continuing to strengthen. Unemployment claims fell this morning to just above the key 300,000 level, and the latest updated economic data confirmed second-quarter GDP growth of 2.5%. This morning, the markets responded to the positive side of the news, pushing the Dow Jones Industrials (DJINDICES:^DJI) up more than 45 points as of 10:50 a.m. EDT.

Among Dow stocks, Nike (NYSE:NKE) is a big winner in advance of its earnings debut as a Dow member, rising 1.2%. The athletic-gear giant earned its place in the Dow because of its long-term success in building what was initially a small niche of the apparel and shoe business into a global empire. Even after decades of success, Nike has continued to grow while also fending off competitors seeking to threaten its dominance. Investors are especially enthusiastic about Nike's ability to raise prices even in tough economic conditions, using its well-marketed brand name to support margins and continue to drive share prices higher.

Microsoft (NASDAQ:MSFT) also helped spur the Dow's upward move. The tech leader's 1% jump came as analysts continue to consider the potential impact of the company's second-generation Surface tablet products. Shareholders hope the powerful Surface Pro 2, which will have Windows 8.1 as its operating system, will behave more like a tablet-PC hybrid and make consumers more comfortable using it for business tasks and other functions needing higher computing capabilities than most rival tablets provide. That's a tough order, given the substantial lead its rivals have, but Microsoft is being smart about catering to its already extensive corporate customer base.

Finally, American Express (NYSE:AXP) has gained 1% after the company said it would sell off a 50% stake in its global business-travel division, enlisting private-equity investors to create a joint venture to hold the business. The move won't affect AmEx cardholders who take advantage of its consumer-travel offerings, but it should assist the company in its efforts to restructure its corporate travel services to reconnect with its business customers.

Fool contributor Dan Caplinger has no position in any stocks mentioned. You can follow him on Twitter @DanCaplinger. The Motley Fool recommends American Express and Nike. The Motley Fool owns shares of Microsoft and Nike. 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.