Acting on panic never helps investors, but it's still a good idea to question why you're really buying individual investments.

Consider defense and aerospace giant Lockheed Martin (NYSE: LMT). Though the defense sector shows staying power, you'll find that a few of the 1,600 Motley Fool CAPS members weighing in on the company offer reasons to be bearish.

Here at The Motley Fool, we like to consider both the good and the bad sides of an investment, so in this article, I'm highlighting three of the main bearish arguments on Lockheed Martin. Be sure to read the bullish side as well, and then weigh in with your own comments below or rate Lockheed Martin in CAPS.                                              

1. Slowing profit growth
Similar to Boeing's (NYSE: BA) drop in first-quarter profits in its defense and space division, Lockheed reported  lower profits in three of its four operating divisions and said its overall quarterly earnings took a hit because of health-care reform. With the drop in earnings and the sizeable pension contributions needed to support the company's retirees, some investors aren't certain about strong earnings growth going forward.

2. Spending peaked
Some analysts believe defense spending in the U.S. has peaked because the Pentagon aims to cut $100 billion in arms programs over the next five years. Indeed, AeroVironment (Nasdaq: AVAV) is facing the effects of tighter spending, with its Raven pilotless drone getting 56% less money in the fiscal 2011 budget. Some investors are adjusting for a new environment where costs are more heavily scrutinized.

3. Making concessions
With Lockheed's move to aim for a fixed-price contract for its F-35 program, it's already feeling -- and responding to -- the government's belt-tightening. U.S. Defense Secretary Robert Gates has already criticized General Electric's (NYSE: GE) alternative engine for the F-35, and with the pressure to keep spending under control, other subcontractors in the program such as United Technologies (NYSE: UTX) and Northrop Grumman (NYSE: NOC) could also feel the pinch.           

To see details of what CAPS members are saying now about Lockheed Martin, just click on over to Motley Fool CAPS and have a look -- or add your own thoughts in the comments box below.