The Dow Jones Industrials (DJINDICES:^DJI) had an interesting week, surviving geopolitical tension as well as some unexpected news from the Federal Reserve to climb higher. Despite a modest decline Friday, the Dow gained 237 points for the week, or roughly 1.5%, bringing the average to within 275 points of its all-time record close on Dec. 31 of last year. Helping to push the average up the most were UnitedHealth Group (NYSE:UNH) and Microsoft (NASDAQ:MSFT), while Nike (NYSE:NKE) and McDonald's (NYSE:MCD) were the biggest drags on the Dow last week.

UnitedHealth's 7.5% gain for the week came as investors have gotten greater confidence about the impact of the Affordable Care Act on the health-insurance industry. A report from the Kaiser Family Foundation generally found that despite all the new policy options under Obamacare, the net impact on market share among existing health insurers was relatively small, allowing UnitedHealth to maintain its leadership role in the industry. With the company having several competitive advantages over its peers, including its international exposure through its Brazilian Amil unit as well as its Optum health-services business, UnitedHealth stands ready to take advantage of changing conditions in the industry.

Microsoft soared more than 6.5% after the company announced that it would release a version of its Office software for the iPad. Optimistic investors pointed to the potential to recoup billions in missed revenue opportunities from making Office available to iOS users on the popular tablet, but perhaps the more important message is that Microsoft is taking aim at mobile from a different angle, and that could help bolster the company's staying power even as PC sales continue to weaken.

On the other side of the coin, Nike's 4% drop largely came Friday, in the aftermath of the shoemaker's Thursday-night earnings report. Despite solid results, Nike's guidance for the future was less confident than shareholders wanted to see, with the company pointing to headwinds from a strong dollar and varying levels of economic growth in its foreign markets. Since joining the Dow last year, Nike has had one of the average's highest valuations of any component, and this week's drop shows just how important it is for the company to sustain growth at the pace investors expect in order to keep its high share price.

Finally, McDonald's fell 2%. The fast-food giant has continued to make moves seeking to bolster its flagging growth, including new menu items like its Petite Breakfast Pastries and the possibility of extending its breakfast hours beyond their current 10:30 a.m. limit. But with headwinds like the recent drop in the value of the Chinese yuan, McDonald's initiatives might well prove insufficient to prevent further same-store sales declines in the future. In an ultra-competitive industry, McDonald's has to assume its leadership role and come up with game-changing moves rather than simply following the crowd.

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