The stock market is starting to show some behavior that's troubling to investors. On a few different occasions this week, the market rose in the morning, only to give up those gains by the end of the day. That phenomenon occurred again today, as the Dow Jones Industrials (^DJI 0.44%) gave up gains of as much as 80 points to finish with a gain of two points, technically breaking its four-day losing streak, but leaving investors concerned about whether a deeper correction could be ahead for the stock market.

Still, not every stock fell prey to the bad mood on Wall Street. Boeing (BA 2.06%) was the biggest gainer in the Dow, rising about 1.5%. Although most of the attention the company got today focused on its most recent sales successes, the bigger picture for Boeing is that it has done huge amounts of business over the past several years, largely offsetting concerns about potential defense budget cuts. The main challenge the aircraft maker faces is delivering on its promises, as production delays, and some design issues, have hampered Boeing's execution for a while.

Wal-Mart (WMT -0.53%) jumped more than 1%. Positive consumer sentiment data might be considered negative for Wal-Mart, which, in the past, has thrived during tough economic times. But analyst Jefferies boosted its outlook on the stock today, upgrading it to a buy, and raising its price target by nearly 20%. If the recent drops in the stock market are correctly foreseeing trouble ahead, it could spell another period of strength for the retail giant.

Finally, tech stocks Microsoft (MSFT 0.29%) and Hewlett-Packard (HPQ 3.62%) both climbed today, with HP finishing up 1.2%, and Microsoft rising 0.9%. In many ways, both companies are facing similar challenges: trying to figure out how to adapt to a changing tech world that is threatening their respective traditional power bases. Microsoft is moving forward with its Surface tablet, but competing tablets from its rivals could overshadow the release. Meanwhile, HP has to overcome double-digit percentage declines in worldwide PC shipments as it seeks a way out of its slump. With Microsoft's Windows 8 coming soon, the focus will return to PCs briefly, but the entire industry needs to figure out how to transition away from PCs if it wants to maintain its long-term growth trajectory.